backlight: use pr_warn() and pr_debug() instead of printk()

Use pr_warn() and pr_debug() instead of printk to allow dynamic debugging.
The pr_fmt prefix for pr_ macros is used.  Also fix checkpatch warnings
as below:

WARNING: Prefer pr_warn(... to printk(KERN_WARNING, ...

[akpm@linux-foundation.org: use KBUILD_MODNAME, per Joe]
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index 1c298d5..a5d0d02 100644
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -5,6 +5,8 @@
  *
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/device.h>
@@ -116,7 +118,7 @@
 
 	mutex_lock(&ld->ops_lock);
 	if (ld->ops && ld->ops->set_power) {
-		pr_debug("lcd: set power to %lu\n", power);
+		pr_debug("set power to %lu\n", power);
 		ld->ops->set_power(ld, power);
 		rc = count;
 	}
@@ -152,7 +154,7 @@
 
 	mutex_lock(&ld->ops_lock);
 	if (ld->ops && ld->ops->set_contrast) {
-		pr_debug("lcd: set contrast to %lu\n", contrast);
+		pr_debug("set contrast to %lu\n", contrast);
 		ld->ops->set_contrast(ld, contrast);
 		rc = count;
 	}
@@ -263,8 +265,8 @@
 {
 	lcd_class = class_create(THIS_MODULE, "lcd");
 	if (IS_ERR(lcd_class)) {
-		printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
-				PTR_ERR(lcd_class));
+		pr_warn("Unable to create backlight class; errno = %ld\n",
+			PTR_ERR(lcd_class));
 		return PTR_ERR(lcd_class);
 	}