Fix the following sparse warnings:

arch/arm/mach-omap2/pm.c:58:6: warning: symbol 'omap2_block_sleep' was not declared. Should it be static?
arch/arm/mach-omap2/pm.c:63:6: warning: symbol 'omap2_allow_sleep' was not declared. Should it be static?
arch/arm/mach-omap2/pm.c:71:12: warning: symbol 'omap_pm_init' was not declared. Should it be static?

arch/arm/mach-omap2/pm34xx.c:49:6: warning: symbol '_omap_sram_idle' was not declared. Should it be static?

arch/arm/mach-omap2/prcm.c:96:5: warning: symbol 'cm_read_mod_reg' was not declared. Should it be static?
arch/arm/mach-omap2/prcm.c:103:6: warning: symbol 'cm_write_mod_reg' was not declared. Should it be static?
arch/arm/mach-omap2/prcm.c:110:5: warning: symbol 'cm_rmw_mod_reg_bits' was not declared. Should it be static?
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>