ARM: imx5: remove imx51 non-DT support files

Since i.MX51 becomes a DT only platform, those non-DT support files can
be removed now.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>

diff --cc arch/arm/mach-imx/Makefile
Simple merge

diff --cc arch/arm/mach-imx/devices-imx51.h
Simple merge

diff --cc arch/arm/mach-imx/ehci-imx5.c
Simple merge

diff --cc arch/arm/mach-imx/ehci.h
Simple merge

diff --cc arch/arm/mach-imx/iomux-mx51.h
Simple merge