msm: ipa: fix double-free of memory

In open/close a2_mux channel, memory can be double-freed in some
error cases. This commit fixes that bug.

Change-Id: Ib554004d60bfb5a2b4e670e22f5a4fa91eaf8adb
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>