mach-snapdragon: set serial number

In the typical case where we chainload from ABL, the serial number is
available in the DT bootargs. Read it out and set the serial#
environment variable so that it can be used by fastboot.

Change-Id: If3af14ef25e3d0b637f9b7e30218a95250f5f1c1
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
diff --git a/arch/arm/mach-snapdragon/qcom-priv.h b/arch/arm/mach-snapdragon/qcom-priv.h
index 0aa61c9..89a4f5f 100644
--- a/arch/arm/mach-snapdragon/qcom-priv.h
+++ b/arch/arm/mach-snapdragon/qcom-priv.h
@@ -2,6 +2,8 @@
 #ifndef __QCOM_PRIV_H__
 #define __QCOM_PRIV_H__
 
+void qcom_set_serialno(void);
+
 #if IS_ENABLED(CONFIG_EFI_HAVE_CAPSULE_SUPPORT)
 void qcom_configure_capsule_updates(void);
 #else