rtc: pxa27x/pxa3xx driver fixes, revised

rtc: pxa27x/pxa3xx driver fixes, revised

Small fixes for the pxa27x/pxa3xx driver

- use platform_driver_probe
- fixed exit paths
- fixed probe sequence
- added missing include
- using linux/io.h instead of asm/io.h

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>