mxs: prefix register acessor macros with 'mxs' prefix

As the register accessing mode is the same for all i.MXS SoCs we ought
to use 'mxs' prefix intead of 'mx28'.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
diff --git a/drivers/usb/host/ehci-mxs.c b/drivers/usb/host/ehci-mxs.c
index e1bd37e..f32df51 100644
--- a/drivers/usb/host/ehci-mxs.c
+++ b/drivers/usb/host/ehci-mxs.c
@@ -75,8 +75,8 @@
 
 	int ret;
 	uint32_t usb_base, cap_base;
-	struct mx28_register_32 *digctl_ctrl =
-		(struct mx28_register_32 *)HW_DIGCTL_CTRL;
+	struct mxs_register_32 *digctl_ctrl =
+		(struct mxs_register_32 *)HW_DIGCTL_CTRL;
 	struct mx28_clkctrl_regs *clkctrl_regs =
 		(struct mx28_clkctrl_regs *)MXS_CLKCTRL_BASE;
 
@@ -119,8 +119,8 @@
 {
 	int ret;
 	uint32_t tmp;
-	struct mx28_register_32 *digctl_ctrl =
-		(struct mx28_register_32 *)HW_DIGCTL_CTRL;
+	struct mxs_register_32 *digctl_ctrl =
+		(struct mxs_register_32 *)HW_DIGCTL_CTRL;
 	struct mx28_clkctrl_regs *clkctrl_regs =
 		(struct mx28_clkctrl_regs *)MXS_CLKCTRL_BASE;