msm: ipa: Initialize function default return type to 0

This fix makes sure to initialize the return type to 0.
This will make sure the effected functions always
return 0 or an error code.

Change-Id: I77ca49ca501d0d69d4d64eba90160819112adcdd
Acked-by: Jyothi Jayanthi <jyothij@qti.qualcomm.com>
Signed-off-by: Michael Adisumarta <madisuma@codeaurora.org>