xtensa/esp32s3: Support malloc from external RAM and internal RAM

[cwespressif]

Summary

This PR intends to enable the separation of Kernel and Userspace heaps in ESP32S3 operating under Flat mode.

This new feature enables the allocation of the entire Userspace heap into SPI RAM and reserving the Internal RAM exclusively for the Kernel heap, which may benefit some timing-constrained Kernel components (e.g. Wi-Fi driver).

Impact

Testing

• Successful execution of ostest in esp32s3-devkit:psram_usrheap defconfig.
• Successful connection to Wi-Fi network using a custom version of esp32s3-devkit:wapi and enable SPIRAM config: CONFIG_ESP32S3_SPIRAM/CONFIG_ESP32S3_SPIRAM_USER_HEAP/CONFIG_XTENSA_IMEM_USE_SEPARATE_HEAP

[yamt]

This new feature enables the allocation of the entire Userspace heap into SPI RAM and reserving the Internal RAM exclusively for the Kernel heap, which may benefit some timing-constrained Kernel components (e.g. Wi-Fi driver).

just curious; did it actually make wifi work better?

[cwespressif]

This new feature enables the allocation of the entire Userspace heap into SPI RAM and reserving the Internal RAM exclusively for the Kernel heap, which may benefit some timing-constrained Kernel components (e.g. Wi-Fi driver).

just curious; did it actually make wifi work better?

• If WiFi internal malloc from external RAM, it will cause the system to block, using this PR can avoid Wi-Fi internal malloc from external RAM. In addition, the kernel drivers uses kmm_malloc to apply for memory from internal RAM rather than external RAM, which can usually avoid some possible performance problems or compatibility issues.

[xiaoxiang781216]

add indent

[cwespressif]

Done

[jerpelea]

please add commit message!