OMAP2+: TWL: make conversion routines static

The uv_to_vsel, vsel_to_uv functions don't need to be exposed to the
world as they are used as function pointers. make them static.

Fixes sparse warnings:
arch/arm/mach-omap2/omap_twl.c:63:15: warning: symbol 'twl4030_vsel_to_uv' was not declared. Should it be static?
arch/arm/mach-omap2/omap_twl.c:68:4: warning: symbol 'twl4030_uv_to_vsel' was not declared. Should it be static?
arch/arm/mach-omap2/omap_twl.c:73:15: warning: symbol 'twl6030_vsel_to_uv' was not declared. Should it be static?
arch/arm/mach-omap2/omap_twl.c:105:4: warning: symbol 'twl6030_uv_to_vsel' was not declared. Should it be static?

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

arch/arm/mach-omap2/omap_twl.c

@@ -60,17 +60,17 @@ static u8 smps_offset;
 
 #define REG_SMPS_OFFSET         0xE0
 
-unsigned long twl4030_vsel_to_uv(const u8 vsel)
+static unsigned long twl4030_vsel_to_uv(const u8 vsel)
 {
 	return (((vsel * 125) + 6000)) * 100;
 }
 
-u8 twl4030_uv_to_vsel(unsigned long uv)
+static u8 twl4030_uv_to_vsel(unsigned long uv)
 {
 	return DIV_ROUND_UP(uv - 600000, 12500);
 }
 
-unsigned long twl6030_vsel_to_uv(const u8 vsel)
+static unsigned long twl6030_vsel_to_uv(const u8 vsel)
 {
 	/*
 	 * In TWL6030 depending on the value of SMPS_OFFSET
@@ -102,7 +102,7 @@ unsigned long twl6030_vsel_to_uv(const u8 vsel)
 		return ((((vsel - 1) * 125) + 6000)) * 100;
 }
 
-u8 twl6030_uv_to_vsel(unsigned long uv)
+static u8 twl6030_uv_to_vsel(unsigned long uv)
 {
 	/*
 	 * In TWL6030 depending on the value of SMPS_OFFSET