soc: swr-mstr: exit irq handler if clock req fails

exit irq handler gracefully if soundwire clock request
fails, so that soundwire registers are not accessed
without clock.

Change-Id: Ic2c9162e49901c7d5c876115f386d0a5a00fd691
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>