ASoC: wcd937x: Fix playback stop issue after SSR/PDR on special hs

If we start playback on special hs after record is done and perform
SSR/PDR then playback gets paused. This happens because ANA_TX_DIV2_CLK
which needs to be enabled for special hs gets disabled after record
is stopped. Maintain a count for ANA_DIV2_CLK to enable/disable it
as required.

Change-Id: Ic73475c83cb16e3c014f35b8d46ee22d2e7a2efd
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>