driver: display: Added extra asserts to SDL display
driver: display: Added extra asserts to SDL display

Added extra asserts to write function of SDL display driver to check if
write is within bounds.

Signed-off-by: Jan Van Winkel <d648848808a4d751aff880668aa63d2d9d94a5a4@dxplore.eu>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr