ep93xx: Remove unnecessary includes of ep93xx-regs.h

Remove the include of ep93xx-regs.h from files which no longer need
it, notably include/mach/hardware.h.

Signed-off-by: Ryan Mallon <rmallon@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: Hartley Sweeten <hsweeten@visionengravers.com>