msm: pcie: remove duplicate call to get aux clk from dt

There is an extra identical call made to check if aux clk
is supported base from PCIe device tree node. There is no
need to do this check twice; therefore, remove the duplicate
call.

Change-Id: If705e98e637287969d68ea2241e62447aa505eb0
Signed-off-by: Tony Truong <truong@codeaurora.org>