Unify pixis_reset altbank across board families

Basically, refactor the CFG_PIXIS_VBOOT_MASK values
into the separate board config files.

Signed-off-by: Jason Jin <Jason.jin@freescale.com>
Signed-off-by: Jon Loeliger <jdl@freescale.com>
diff --git a/board/freescale/common/pixis.c b/board/freescale/common/pixis.c
index fd99a93..45dcf4d 100644
--- a/board/freescale/common/pixis.c
+++ b/board/freescale/common/pixis.c
@@ -207,13 +207,16 @@
 	out8(PIXIS_BASE + PIXIS_VCFGEN1, tmp);
 }
 
+#ifndef CFG_PIXIS_VBOOT_MASK
+#define CFG_PIXIS_VBOOT_MASK	0x40
+#endif
 
 void set_altbank(void)
 {
 	u8 tmp;
 
 	tmp = in8(PIXIS_BASE + PIXIS_VBOOT);
-	tmp ^= 0x40;
+	tmp ^= CFG_PIXIS_VBOOT_MASK;
 
 	out8(PIXIS_BASE + PIXIS_VBOOT, tmp);
 }