mx6: Remove duplication of iomuxc structure

There is no need to keep iomuxc_base_regs structure as it serves the exact same
purpose of the iomuxc structure, which is to provide access to the GPR
registers.

The additional fields of iomuxc_base_regs are not used. Other advantage of
'iomuxc' is that it has a shorter name and the variable declarations can fit
into a single line.

So remove iomuxc_base_regs structure and use iomuxc instead.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/board/freescale/mx6slevk/mx6slevk.c b/board/freescale/mx6slevk/mx6slevk.c
index d2b64cc..a990b4c 100644
--- a/board/freescale/mx6slevk/mx6slevk.c
+++ b/board/freescale/mx6slevk/mx6slevk.c
@@ -130,8 +130,7 @@
 
 static int setup_fec(void)
 {
-	struct iomuxc_base_regs *iomuxc_regs =
-				(struct iomuxc_base_regs *)IOMUXC_BASE_ADDR;
+	struct iomuxc *iomuxc_regs = (struct iomuxc *)IOMUXC_BASE_ADDR;
 	int ret;
 
 	/* clear gpr1[14], gpr1[18:17] to select anatop clock */