ep93xx: Move crunch code to mach-ep93xx directory

The crunch code in arch/arm/kernel is specific to the EP93xx. Move it
to the mach-ep93xx directory. This removes the need for the
EP93XX_SYSCON defines to be exported to arch/arm/kernel.

Signed-off-by: Ryan Mallon <rmallon@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: Hartley Sweeten <hsweeten@visionengravers.com>