dm: backlight: Add CONFIG_BACKLIGHT_PWM

Add a config to select individually the driver for PWM backlights.
Manage "depends on" to be backyard compatible.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

drivers/video/Kconfig

@@ -14,6 +14,17 @@ config DM_VIDEO
 	  option compiles in the video uclass and routes all LCD/video access
 	  through this.
 
+config BACKLIGHT_PWM
+	bool "Generic PWM based Backlight Driver"
+	depends on DM_VIDEO && DM_PWM
+	default y
+	help
+	  If you have a LCD backlight adjustable by PWM, say Y to enable
+	  this driver.
+	  This driver can be use with "simple-panel" and
+	  it understands the standard device tree
+	  (leds/backlight/pwm-backlight.txt)
+
 config VIDEO_BPP8
 	bool "Support 8-bit-per-pixel displays"
 	depends on DM_VIDEO

drivers/video/Makefile

@@ -11,9 +11,7 @@ obj-$(CONFIG_DM_VIDEO) += backlight-uclass.o
 obj-$(CONFIG_DM_VIDEO) += panel-uclass.o simple_panel.o
 obj-$(CONFIG_DM_VIDEO) += video-uclass.o vidconsole-uclass.o
 obj-$(CONFIG_DM_VIDEO) += video_bmp.o
-ifdef CONFIG_DM_VIDEO
-obj-$(CONFIG_DM_PWM) += pwm_backlight.o
-endif
+obj-$(CONFIG_BACKLIGHT_PWM) += pwm_backlight.o
 obj-$(CONFIG_CONSOLE_NORMAL) += console_normal.o
 obj-$(CONFIG_CONSOLE_ROTATION) += console_rotate.o
 obj-$(CONFIG_CONSOLE_TRUETYPE) += console_truetype.o fonts/