ARM: OMAP: Correct save_boot_params and replace with 'C' function

Currently save_boot_params saves the boot parameters passed
from romcode. But this is not stored in a writable location
consistently. So the current code would not work for a
'XIP' boot. Change this by saving the boot parameters in
'gd' which is always writable. Also add a 'C' function
instead of an assembly code that is more readable.

Signed-off-by: Sricharan R <r.sricharan@ti.com>
diff --git a/arch/arm/include/asm/omap_boot.h b/arch/arm/include/asm/omap_boot.h
index 87a9530..a803965 100644
--- a/arch/arm/include/asm/omap_boot.h
+++ b/arch/arm/include/asm/omap_boot.h
@@ -45,5 +45,6 @@
 	unsigned char omap_bootdevice;
 	unsigned char reset_reason;
 	unsigned char ch_flags;
+	unsigned long omap_bootmode;
 };
 #endif