ENGR00237742 busfreq:fix IPG_PERCLK will be decreased to 6M once exit low bus

ENGR00237742 busfreq:fix IPG_PERCLK will be decreased to 6M once exit low bus

on Sabresd board, IPG_PERCLK will be fixed on 6Mhz once system enter low bus,
and never restore to 22Mhz which be set in boot.  It means some device clock
which sourcing from IPG_PERCLK such as I2C will be slow down. The root cause is
that there is workaround for GPT timer of Arik TO1.0 in mx6_ddr_freq.S. GPT
clock source from IPG_PERCLK on TO1.0 and should be fixed on 6Mhz. But for
TO1.1 and TO1.2 ,the workaround should be removed.
Signed-off-by: Robin Gong <B38343@freescale.com>