[ARM] pxa: shut up CLOCK_EVT_MODE_RESUME warning

Resolve:
  CC      arch/arm/mach-pxa/time.o
arch/arm/mach-pxa/time.c: In function `pxa_osmr0_set_mode':
arch/arm/mach-pxa/time.c:154: warning: enumeration value `CLOCK_EVT_MODE_RESUME' not handled in switch

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