ARM: build: Fix compile error unsupport VFP

This patch is to fix the build error with *-gnueabihf-* toolchain, since u-boot does not support to use VFP register arguments.

Change-Id: I1b3eb17080494bccbd81f6485ccb10559fcab3b2
Signed-off-by: Dongjin Kim <tobetter@gmail.com>