[ARM] pxa: Fix RCSR handling

Related to d3930614.

RCSR is only present on PXA2xx CPUs, not on PXA3xx CPUs.  Therefore,
we should not be unconditionally writing to RCSR from generic code.

Since we now clear the RCSR status from the SoC specific PXA PM code
and before reset in the arch_reset() function, the duplication in
the corgi, poodle, spitz and tosa code can be removed.

Acked-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>