arm: omap1: make some functions static

Make some functions static to get rid of the following sparse warnings:

arch/arm/mach-omap1/mcbsp.c:177:12: warning: symbol 'omap1_mcbsp_init' was not declared. Should it be static?
arch/arm/mach-omap1/mux.c:346:22: warning: symbol 'omap1_cfg_reg' was not declared. Should it be static?
arch/arm/plat-omap/dma.c:177:5: warning: symbol 'omap_dma_in_1510_mode' was not declared. Should it be static?
arch/arm/plat-omap/sram.c:273:12: warning: symbol 'omap1_sram_init' was not declared. Should it be static?

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>