imx: mx6 add PAD_CTL_SPEED_LOW for i.MX6SX/UL

PAD_CTL_SPEED_LOW for i.MX6SX/UL is (0 << 6)

Signed-off-by: Ye.Li <B37916@freescale.com>
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
1 file changed