ARM: SAMSUNG: Initialize PWM backlight enable_gpio field

The GPIO API defines 0 as being a valid GPIO number, so this field needs
to be initialized explicitly.

Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/mach-s3c64xx/mach-hmt.c

@@ -114,6 +114,7 @@ static struct platform_pwm_backlight_data hmt_backlight_data = {
 	.max_brightness	= 100 * 256,
 	.dft_brightness	= 40 * 256,
 	.pwm_period_ns	= 1000000000 / (100 * 256 * 20),
+	.enable_gpio	= -1,
 	.init		= hmt_bl_init,
 	.notify		= hmt_bl_notify,
 	.exit		= hmt_bl_exit,