Fix define for MPC5121 ADS board.

Originally the Makefile defines CONFIG_ADS5121_REV2 when configuring
for board mpc5121ads_rev2. The config in include/configs/mpc5121ads.h
expects a define CONFIG_MPC5121ADS_REV2 for this.
Therefore there are two defines used but only 1 is defined.
This patch renames references to CONFIG_ADS5121_REV2 to CONFIG_MPC5121ADS_REV2
to have one common define.

This patch fixes faulty mem size detection caused by wrong config in
include/configs/mpc5121ads.h

Signed-off-by: Mark Vels <mark.vels@team-embedded.nl>
diff --git a/board/freescale/mpc5121ads/mpc5121ads.c b/board/freescale/mpc5121ads/mpc5121ads.c
index a84644d..8cc6853 100644
--- a/board/freescale/mpc5121ads/mpc5121ads.c
+++ b/board/freescale/mpc5121ads/mpc5121ads.c
@@ -102,7 +102,7 @@
 	 * write commands in order to establish the device ID.
 	 */
 
-#ifdef CONFIG_ADS5121_REV2
+#ifdef CONFIG_MPC5121ADS_REV2
 	out_8((u8 *)(CONFIG_SYS_CPLD_BASE + 0x08), 0xC1);
 #else
 	if (in_8((u8 *)(CONFIG_SYS_CPLD_BASE + 0x08)) & 0x04) {
@@ -329,7 +329,7 @@
 	volatile immap_t *im = (immap_t *) CONFIG_SYS_IMMR;
 	u32 spridr = in_be32(&im->sysconf.spridr);
 
-	printf ("Board: ADS5121 rev. 0x%04x (CPLD rev. 0x%02x)\n",
+	printf ("Board: MPC5121ADS rev. 0x%04x (CPLD rev. 0x%02x)\n",
 		brd_rev, cpld_rev);
 
 	/* initialize function mux & slew rate IO inter alia on IO Pins  */