ARM: sa11x0/pxa: convert OS timer registers to IOMEM

Make the OS timer registers have IOMEM like properities so they can
be passed to readl_relaxed/writel_relaxed() et.al. rather than being
straight volatile dereferences.

This fixes these warnings:

arch/arm/mach-sa1100/time.c: In function 'sa1100_timer_init':
arch/arm/mach-sa1100/time.c:104: warning: passing argument 1 of 'clocksource_mmio_init' discards qualifiers from pointer target type
arch/arm/mach-pxa/time.c: In function 'pxa_timer_init':
arch/arm/mach-pxa/time.c:126: warning: passing argument 1 of 'clocksource_mmio_init' discards qualifiers from pointer target type

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