MLK-18152-2 mx6sxsabresd: Update board codes to align with v2020.04

MLK-18152-2 mx6sxsabresd: Update board codes to align with v2020.04

Add emmc support which needs board rework.
Add I2C2.
Update DM PMIC settings and LDO bypass support.
Add BMODE support.
Add LVDS and LCD splash screen support
Add PCI power and reset GPIO and disable PCI at default.
Update QSPI settings for QSPI boot and M4 fastup.
Update environment settings

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit e74716b6e78f016226dc9f800b04574f545d9367)
(cherry picked from commit f3dd07286dc39d3028deaedf5dc1668929cbfd29)
(cherry picked from commit 462883d1a88e59fd2b854c3f751e75a329fad500)