omap_hsmmc.c: Fix build warning on non-omap3

It was incorrect to always include "asm/arch-omap3/mux.h" constantly.
This introduced warnings on non-omap3 where certain values will conflict
between the various families.  Conditionally guard the inclusion in
order to correct the problem.

Fixes: 6aca17c9b7e8 ("drivers: mmc: omap_hsmmc: Fix IO Buffer on OMAP36xx")
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/mmc/omap_hsmmc.c b/drivers/mmc/omap_hsmmc.c
index b63ce56..7ed5328 100644
--- a/drivers/mmc/omap_hsmmc.c
+++ b/drivers/mmc/omap_hsmmc.c
@@ -37,8 +37,10 @@
 #include <asm/gpio.h>
 #include <asm/arch/sys_proto.h>
 #endif
+#ifdef CONFIG_MMC_OMAP36XX_PINS
+#include <asm/arch/mux.h>
+#endif
 #include <dm.h>
-#include <asm/arch-omap3/mux.h>
 
 DECLARE_GLOBAL_DATA_PTR;