drivers: display: Select LED_STRIP when LED_STRIP_MATRIX is enabled

The LED_STRIP driver is not enabled by default on all boards. As a result,
building the LED_STRIP_MATRIX display driver fails if LED_STRIP is not
manually enabled.

To address this, this commit changes the dependency from `depends on` to
`select`, ensuring that the required driver is automatically enabled and
build failures are avoided.

Signed-off-by: Chen Xingyu <hi@xingrz.me>

drivers/display/Kconfig.led_strip_matrix

@@ -5,7 +5,7 @@ config LED_STRIP_MATRIX
 	bool "LED strip matrix display driver"
 	default y
 	depends on DT_HAS_LED_STRIP_MATRIX_ENABLED
-	depends on LED_STRIP
+	select LED_STRIP
 	help
 	  Enable LED strip matrix display (LED strip arranged in
 	  a grid pattern) driver.