imx: mx7ulp_evk: enable mmc/regulator support

Enable MMC support.
The fsl sdhc driver needs regulator to enable power, so enable
regulator support.

And bootcmd and more env.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>