dev: pm8x41: Add feedback interface for WLED

Some of devices have backlight not on issue in LK, like
QRD8x26 DVT and 8x26 MTP. Fix this by selecting LED1
output as feedback node for the Boost.

By the way, fix an issue in pm8x41 wled interface for
iled_sync control.

Change-Id: Ibad6f7ad42b43f5d512c40d23d2afc9386b2541b
diff --git a/target/msm8226/target_display.c b/target/msm8226/target_display.c
index 5b719cc..c83b68c 100755
--- a/target/msm8226/target_display.c
+++ b/target/msm8226/target_display.c
@@ -49,7 +49,8 @@
 	.led1_brightness = (0x0F << 8) | 0xEF,
 	.max_duty_cycle  = 0x01,
 	.ovp = 0x0,
-	.full_current_scale = 0x19
+	.full_current_scale = 0x19,
+	.fdbck = 0x1
 };
 
 int target_backlight_ctrl(uint8_t enable)