MLK-18153-1 dts: mx6slevk: Update DTS and DTSi to align with v2020.04

MLK-18153-1 dts: mx6slevk: Update DTS and DTSi to align with v2020.04

Copy the DTS and DTSi from 4.14 kernel.

Changes in DTS specified for u-boot:
1. Add alias for mmc and usb
2. Add pin settings for i2c bus force idle
3. Change PMIC node name
4. Update model name to remove freescale

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit e669373fc5f861750b2b7b59cde6c31c43cf61fb)
(cherry picked from commit 877d09b0d104db8e377aa6e213b7cee46217fbbd)
(cherry picked from commit 1c0c39e41ac9e4caea0452a242d6f9245231e09f)