ASoC: wcd937x: Add alias for in2p clamp register

Add alias for in2p clamp register to check in2p
clamp state in insertion irq and ignore the interrupt
if the clamp is already set.

Change-Id: Ibd4ff2cef8690894a01072e74ce130f824656f5d
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>