ARM clock is sourcing from pll1_sw, and pll1_sw can be either from
pll1_sys or step, so we should enable arm clock during clock
initialization instead of pll1_sys, otherwise, arm clock's usecount
would be incorrect and PLL1 will never be disabled even it is not
used.
Signed-off-by: NAnson Huang <b20788@freescale.com>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>