MX5:MX53: add initial support for MX53EVK board

Add initial support for MX53EVK board support.
FEC, SD/MMC, UART, I2C, have been supported.

Signed-off-by: Jason Liu <r64343@freescale.com>
diff --git a/boards.cfg b/boards.cfg
index 141b143..3ad8bc4 100644
--- a/boards.cfg
+++ b/boards.cfg
@@ -106,6 +106,7 @@
 edminiv2                     arm         arm926ejs   -                   LaCie          orion5x
 ca9x4_ct_vxp                 arm         armv7       vexpress            armltd
 mx51evk                      arm         armv7       mx51evk             freescale      mx5
+mx53evk                      arm         armv7       mx53evk             freescale      mx5
 vision2                      arm         armv7       vision2             ttcontrol      mx5
 omap3_overo                  arm         armv7       overo               -              omap3
 omap3_pandora                arm         armv7       pandora             -              omap3