ENGR00180955 mx6q sabresd snvs TKT104835: fix long press ONOFF failed in u-boot

Need set Power Supply Glitch to 0x41736166 and clear Power Supply Glitch
Detect bit when POR or reboot or power on, otherwise system could not be
power off anymore, it will power up auto agian. These steps may be move to
ROM code or fix by soc team in the future(PDM ticket number:TKT104835),
anyway,u-boot fix the issue firsly.
Signed-off-by: Robin Gong <b38343@freescale.com>

Signed-off-by: Robin Gong <B38343@freescale.com>