MLK-12534 mx6: shutdown vddpu and PCIE phy to save power

MLK-12534 mx6: shutdown vddpu and PCIE phy to save power

Shutdown VDDPU and PCIE phy to save power.

For PCIE, the i.MX6SL and i.MX6UL does not have this module,
so don't need it.

For VDDPU, the i.MX6UL does not have GPU, does not need it. And on
i.MX6QP there is narrow window that PRE driver is ready but GPU driver probe later,
and the later GPU driver turn on PU may cause 'PRE hang' issue. To simplify
thing, do not turn off PU in u-boot.

Reference:
commit: 6b0787b726e2ff32210d742d93ecd3f4bb2ae402
commit: 4bd0032c0eba50fa0caf43f50f735a3cfbe36a8d

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit 5c96ea91fe89c67991c929c9b39ffaa940d28391)