arch/arm: Fix the compilation error

[xiaoqizhan]

When the macro SDADC_HAVE_TIMER is enabled, a compilation error will occur due to the missing semicolon after the variable.

Note: Please adhere to Contributing Guidelines.

Summary

This PR fixes a compilation error caused by a missing semicolon at the end of the jextsel variable declaration. The error is triggered when the macro SDADC_HAVE_TIMER is enabled: the jextsel variable (used to store the JEXTSEL value for the SDADC block) lacks a trailing semicolon, which violates C syntax rules and blocks the build process. This change only adds the missing semicolon to the jextsel variable definition under the SDADC_HAVE_TIMER macro guard, with no other logic modifications—ensuring compliance with C syntax and resolving the compilation failure.

Impact

Build process: Resolves the compilation error that occurs when SDADC_HAVE_TIMER is enabled; no impact on build logic or output for scenarios where this macro is disabled.

Users/Hardware: No functional changes to SDADC or timer-related features; the behavior of the SDADC block and associated timer (base address, PCLK frequency, conversion frequency) remains unchanged. Only fixes a syntax error that prevented successful compilation for users enabling the SDADC_HAVE_TIMER macro.

Compatibility/Security: Fully backward-compatible—no breaking changes to existing code, APIs, or hardware interactions. No security implications as this is a pure syntax correction.

Documentation: No changes to documentation are required, as this is a bug fix for a syntax error rather than a feature modification.

Testing

1. Host Machine Information
   Host OS: Ubuntu 22.04 LTS (x86_64)
   Toolchain: GNU Arm Embedded Toolchain 10.3-2021.10 (arm-none-eabi-gcc)
   Build system: GNU Make 4.3
2. Tested Board & Configuration
   Target board: STM32H743I-EVAL (SDADC peripheral and timer functionality are supported)
   Configuration: Enabled the SDADC_HAVE_TIMER macro via menuconfig (Configuration → Drivers → Analog → SDADC → Enable timer support for SDADC)
3. Test Logs (Key Snippets)
   Pre-fix compilation error log:
   plaintext
   CC: drivers/analog/stm32_sdadc.c
   ../drivers/analog/stm32_sdadc.c:456:16: error: expected ';' before 'uint32_t'
   uint32_t pclck; /* The PCLK frequency that drives this timer /
   ^~~~~~
   ;
   ../drivers/analog/stm32_sdadc.c:455:16: note: in this expansion of SDADC_HAVE_TIMER
   uint32_t jextsel / JEXTSEL value used by this SDADC block */
   ^~~~~~~
   make: *** [Makefile:1247: drivers/analog/stm32_sdadc.o] Error 1
   PRs without testing information will not be accepted. We will
   request test logs.
   Post-fix build success log:
   plaintext
   CC: drivers/analog/stm32_sdadc.c
   AR: drivers/analog/libanalog.a
   LD: nuttx.elf
   OBJCOPY: nuttx.bin
   OBJDUMP: nuttx.dis
4. Additional Verification
   Checked all other code paths under SDADC_HAVE_TIMER (timer base address, PCLK frequency, conversion frequency variables) to confirm no other syntax issues.
   Tested builds with SDADC_HAVE_TIMER disabled: no compilation warnings/errors, and existing SDADC functionality remains intact.