linux-phytec-fsl

MLK-13405-1 ARM: dts: add usdhc2 support for imx6sll-evk

For imx6sll-evk board, if eMMC connected, all the pad of
eMMC should be fixed to 1.8v. Otherwise the current leakage
will pull up the VCCQ to 2.6v, which will impatch usdhc1
and usdhc3 SD3.0 voltage switch.

This patch set the LVE of pad SD2_RST and SD2_STROBE, and
config the vqmmc to fixed 1.8v, make sure the driver set
pad I/O voltage of usdhc2 fixed to 1.8v, not impact the
VCCQ which support usdhc1 and usdhc3 SD3.0 1.8v voltage.

And accord to IC suggestion, clock and strobe pad need to
config as pull-down. So change all the clock/strobe pad's
PUS to 0.

eMMC data4/5 has branch on evk board, which make the data
signal quality very bad, need to cut off these branch of
data4/5, this hardware rework is hard to do on all the evk
board. So currently HS400 do not enable, just support eMMC
HS200 mode.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>