omap3_mmc: Encapsulate twl4030 under option CONFIG_TWL4030_POWER

Fixes the build/compilation error if we try to re-use the omap3_mmc code
without TWL4030_POWER.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>

drivers/mmc/omap3_mmc.c

@@ -63,7 +63,9 @@ unsigned char mmc_board_init(void)
 {
 	t2_t *t2_base = (t2_t *)T2_BASE;
 
+#if defined(CONFIG_TWL4030_POWER)
 	twl4030_power_mmc_init();
+#endif
 
 	writel(readl(&t2_base->pbias_lite) | PBIASLITEPWRDNZ1 |
 		PBIASSPEEDCTRL0 | PBIASLITEPWRDNZ0,