gpio: syscon: fix excess struct member build warning

Fix the build warning with W=1 flag,
"Excess struct member 'compatible' description in 'syscon_gpio_data' "
by removing the documentation for the non existent member.
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20240902-b4-gpio-fix-v1-1-49a997994fa5@ti.comSigned-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-syscon.c

@@ -23,7 +23,6 @@
 
 /**
  * struct syscon_gpio_data - Configuration for the device.
- * @compatible:		SYSCON driver compatible string.
  * @flags:		Set of GPIO_SYSCON_FEAT_ flags:
  *			GPIO_SYSCON_FEAT_IN:	GPIOs supports input,
  *			GPIO_SYSCON_FEAT_OUT:	GPIOs supports output,