OMAP4: Panda: Disable CMD_NFS

This patch fixes the Panda build after commit 6d8962e8
by explicitly disabling CMD_NFS

>From the commit message for "Switch from archive libraries to partial linking":

This commit reveals board configurations that exclude some features but
include source files that depend these disabled features in the build,
resulting in undefined symbols.  Known such cases include:

- disabling CMD_NET but not CMD_NFS;
- enabling CONFIG_OF_LIBFDT but not CONFIG_QE.
Signed-off-by: NSteve Sakoman <steve.sakoman@linaro.org>
Signed-off-by: NSandeep Paulraj <s-paulraj@ti.com>

include/configs/omap4_panda.h

@@ -134,6 +134,7 @@
 
 /* Disabled commands */
 #undef CONFIG_CMD_NET
+#undef CONFIG_CMD_NFS
 #undef CONFIG_CMD_FPGA		/* FPGA configuration Support   */
 #undef CONFIG_CMD_IMLS		/* List all found images        */