AM35x: Enable OMAP_MUX in defconfig

Enabling OMAP_MUX in defconfig as it is required for EHCI to work.
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/configs/am3517_evm_defconfig

@@ -201,7 +201,7 @@ CONFIG_ARCH_OMAP3=y
 # CONFIG_OMAP_DEBUG_POWERDOMAIN is not set
 # CONFIG_OMAP_DEBUG_CLOCKDOMAIN is not set
 CONFIG_OMAP_RESET_CLOCKS=y
-# CONFIG_OMAP_MUX is not set
+CONFIG_OMAP_MUX=y
 # CONFIG_OMAP_MCBSP is not set
 # CONFIG_OMAP_MBOX_FWK is not set
 # CONFIG_OMAP_MPU_TIMER is not set