ASoC: msm: Fix deadlock issue in external EC function

In external EC msm_routing_ext_ec_put function, when DAPM
mux update function is called backend and front end dai are
linked. At this point backend HW param function is called.
To update back end structure routing lock is acquired. This
fix is to avoid the deadlock situation.

CRs-fixed: 485954
Change-Id: I91fcee0be02849837db909429ad74e1010db7b12
Signed-off-by: Venkat Sudhir <vsudhir@codeaurora.org>