soc: swr-mstr: Fix headset detect issue due to master.num_dev not updated

Headset is not detected sometimes due to master.num_dev not being
updated when we call GET_ENUM_SLAVE_STATUS as get_logical address
may not have been called. Also enable slave irq only when
swr wokeup from clk stop and not when master is already up.
This will prevent valid irq to be discarded as spurious irq.

Change-Id: I00284e9340668c853d0bd604fe66801118982780
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>