clk: qcom: alpha-pll: Check for PLL run condition for Fabia PLL

The PLL could be enabled previously to HLOS and sourcing to the RCG. In
those cases where the clock driver receives the enable request it would
temporarily disable the PLL output. Thus handle such condition if PLL is
already enabled.

Change-Id: I75118c09ff67a35d866dabea4a948e7401915f9a
Signed-off-by: Taniya Das <tdas@codeaurora.org>