ARM i.MX: Merge i.MX5 support into mach-imx

This patch moves the contents of arch/arm/mach-mx5 to arch/arm/mach-imx
and adjusts the Makefile/Kconfig entries in a way that it's possible
to compile i.MX5 together with i.MX3/6.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>