MLK-13405-3 mx6sll-evk: change the eMMC reset pad to 1.8v

eMMC is connected fixed to 1.8v, so need to set the LVE of pad
sd2_rst. Also need to set the VSELECT to change all the eMMC pad
(cmd, clk, data) I/O voltage to 1.8v. Otherwise, the current leak
will pull up the VCCQ from 1.8v to 2.6v, which will impact SD1 and
SD3 voltage switch.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
(cherry picked from commit 0df1d653)