ENGR00216031 [MX6]Need to force bus freq to highest point when suspend

ENGR00216031 [MX6]Need to force bus freq to highest point when suspend

1. When bus freq is at 400M setpoint, currently bus freq will not
set to high setpoint when suspend, but some drivers which need
high bus freq enable clock before bus freq resume, so the request
of high bus freq will be ignore until next high bus freq device is
enabled,it will result in some devices need high bus freq but bus freq
dirver stay at med setpoint. So we need to force bus freq to
highest setpoint before suspend to avoid such scenario.

2. Clean up PU LDO turn on/off, move to regulator driver and maintain by
VPU and GPU driver.

Signed-off-by: Anson Huang <b20788@freescale.com>