msm8960: write reboot reason before reset

fastboot reboot-bootloader requires reboot reason to be set to work properly.
diff --git a/target/msm8960/init.c b/target/msm8960/init.c
index 5e5d107..9047829 100644
--- a/target/msm8960/init.c
+++ b/target/msm8960/init.c
@@ -270,6 +270,8 @@
 
 void reboot_device(unsigned reboot_reason)
 {
+	writel(reboot_reason, RESTART_REASON_ADDR);
+
 	/* Actually reset the chip */
 	pm8921_config_reset_pwr_off(1);
 	writel(0, MSM_PSHOLD_CTL_SU);