drm/gma500: correct kerneldoc

Correct kerneldoc (remove wrong /** marker and adjust function name) to
fix W=1 warnings:

  drivers/gpu/drm/gma500/cdv_intel_lvds.c:27: warning:
    expecting prototype for LVDS I2C backlight control macros(). Prototype was for BRIGHTNESS_MAX_LEVEL() instead

  drivers/gpu/drm/gma500/intel_gmbus.c:386: warning:
    expecting prototype for intel_gmbus_setup(). Prototype was for gma_intel_setup_gmbus() instead
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210419081807.68000-1-krzysztof.kozlowski@canonical.com

drivers/gpu/drm/gma500/cdv_intel_lvds.c

@@ -21,7 +21,7 @@
 #include "psb_intel_drv.h"
 #include "psb_intel_reg.h"
 
-/**
+/*
  * LVDS I2C backlight control macros
  */
 #define BRIGHTNESS_MAX_LEVEL 100

drivers/gpu/drm/gma500/intel_gmbus.c

@@ -379,7 +379,7 @@ static const struct i2c_algorithm gmbus_algorithm = {
 };
 
 /**
- * intel_gmbus_setup - instantiate all Intel i2c GMBuses
+ * gma_intel_setup_gmbus() - instantiate all Intel i2c GMBuses
  * @dev: DRM device
  */
 int gma_intel_setup_gmbus(struct drm_device *dev)