msm: ipa3: Release the IPA lock acquired

In ipa3_rest_rt we are returning from it without unlocking
the lock acquired leading to deadlock issue. Added code to
release the lock acquired.

Change-Id: I9ab6919c6c2f881a580848a578c9429921e92f08
Signed-off-by: Praveen Kurapati <pkurapat@codeaurora.org>