mt7620: fix missing kernel config symbol

Fixes following missing kernel config symbol after adding GPIO watchdog:

  Software watchdog (SOFT_WATCHDOG) [M/n/y/?] m
  Watchdog device controlled through GPIO-line (GPIO_WATCHDOG) [Y/n/m/?] y
    Register the watchdog as early as possible (GPIO_WATCHDOG_ARCH_INITCALL) [N/y/?] (NEW)

Fixes: 1a97c03 ("rampis: feed zbt-we1026 external watchdog")
Signed-off-by: Petr Štetiar <ynezz@true.cz>

target/linux/ramips/mt7620/config-5.10

@@ -68,6 +68,7 @@ CONFIG_GPIOLIB=y
 # CONFIG_GPIO_MT7621 is not set
 CONFIG_GPIO_RALINK=y
 CONFIG_GPIO_WATCHDOG=y
+# CONFIG_GPIO_WATCHDOG_ARCH_INITCALL is not set
 CONFIG_HANDLE_DOMAIN_IRQ=y
 CONFIG_HARDWARE_WATCHPOINTS=y
 CONFIG_HAS_DMA=y