drivers/video/backlight/l4f00242t03.c: prevent unbalanced calls to regulator enable/disable

Otherwise a double call to:
$ echo 4 > /sys/class/lcd/l4f00242t03/lcd_power
Will, the first power down the lcd and regulators correctly and the
second produce an unbalanced call to regulator disable.

Signed-off-by: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/backlight/l4f00242t03.c

@@ -134,10 +134,12 @@ static int l4f00242t03_lcd_power_set(struct lcd_device *ld, int power)
 		}
 	} else {
 		/* power == FB_BLANK_POWERDOWN */
-		/* Clear the screen before shutting down */
-		spi_write(spi, (const u8 *)&disoff, sizeof(u16));
-		msleep(60);
-		l4f00242t03_lcd_powerdown(spi);
+		if (priv->lcd_state != FB_BLANK_POWERDOWN) {
+			/* Clear the screen before shutting down */
+			spi_write(spi, (const u8 *)&disoff, sizeof(u16));
+			msleep(60);
+			l4f00242t03_lcd_powerdown(spi);
+		}
 	}
 
 	priv->lcd_state = power;