ARM: PXA: fix includes in pxa2xx_cm_x2xx PCMCIA driver

The includes in the pxa2xx_cm_x2xx PCMCIA driver are rather random;
the driver doesn't require anything from these headers except the
cpu_is_xxx() macros which come from another include.

The concern is that it's getting these definitions via mach/system.h,
which is supposed to only be included by arch/arm/kernel/process.c.
As this header is scheduled for cleanup (and elimination) keeping
the status quo will cause build errors.  So lets fix properly and
independent of the future work.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>