MLK-9723-3: include: imx6q-iomuxc-gpr: add bit description for MQS

Add MQS's bit description in gpr header file.

Signed-off-by: Shengjiu Wang <shengjiu.wang@freescale.com>
(cherry picked from commit 1e576de4b46a0fadd1c8df7f08229ac759e765f5)
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>
Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>