asoc: ext-clk: Allow clock probe without pinctrl for lpass nodes

Currently audio ref clock probe for lpass clock nodes require
pinctrl entry as mandatory. For bolero lpass clocks, there is
no pinctrl required. Allow audio ref clock probe to proceed
with pinctrl based on property of use-pinctrl set to non-zero
value from dtsi.

Change-Id: Ide4a10e89672f0adefd2e0d99830c38191119dfc
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>