da850evm: add mtdpart and ubi commands with NAND support

This patch enables also the mtdpart, ubi and ubifs commands when NAND support
is enabled.

Signed-off-by: Ben <Gardiner&lt;bengardiner@nanometrics.ca>
To: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>