drm/bridge: Improve the help text for DRM_ANALOGIX_ANX78XX

Improve the help text for DRM_ANALOGIX_ANX78XX by adding the missing
"power" word.

After this change the help text matches with the ANX7814
product description from the Analogix website:

https://www.analogix.com/en/products/convertersbridges/anx7814Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190722194049.20761-1-festevam@gmail.com

drivers/gpu/drm/bridge/Kconfig

@@ -21,7 +21,7 @@ config DRM_ANALOGIX_ANX78XX
 	select DRM_KMS_HELPER
 	select REGMAP_I2C
 	---help---
-	  ANX78XX is an ultra-low Full-HD SlimPort transmitter
+	  ANX78XX is an ultra-low power Full-HD SlimPort transmitter
 	  designed for portable devices. The ANX78XX transforms
 	  the HDMI output of an application processor to MyDP
 	  or DisplayPort.