OMAP4: SDP4430: Disable CMD_NFS

This patch fixes the SDB4430 build after commit 6d8962e814
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: Dirk Behme <dirk.behme@googlemail.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>

include/configs/omap4_sdp4430.h

@@ -139,6 +139,7 @@
 
 /* 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        */