Patch from Ian Campbell

The include of asm/arch/pxa-regs.h has been removed from
asm-arm/arch-pxa/hardware.h and now needs to be included
from the relevant files. 

I have verified the fixes to arch/arm/mach-pxa/sleep.S and 
drivers/char/watchdog/sa1100_wdt.c myself. My local tree
has other changes to include/asm-arm/arch-pxa/serial.h
but I beleive that the attached is necessary and correct.

Signed-off-by: Ian Campbell