omap1: pm_bus: Fix compilation warning

Fix following compilation warning:
arch/arm/mach-omap1/pm_bus.c: In function 'omap1_pm_runtime_resume':
arch/arm/mach-omap1/pm_bus.c:51: warning: unused variable 'ret'

Signed-off-by: Marek Belisko <marek.belisko@open-nandra.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>