[qsd8250]: Add usb charging support in LK bootloader.

Add usb battery charging support for qsd8250_surf and qsd8250_ffa
targets in lk bootloader. USB charging is enabled only when
device goes into fastboot mode.
diff --git a/target/msm7627_ffa/init.c b/target/msm7627_ffa/init.c
index 739beec..9331c29 100644
--- a/target/msm7627_ffa/init.c
+++ b/target/msm7627_ffa/init.c
@@ -184,3 +184,7 @@
     }
     return mode[0];
 }
+
+void target_battery_charging_enable(unsigned enable, unsigned disconnect)
+{
+}