Put brackets around AIDL_RETURN macro

This makes the VALUE_OR_RETURN_ILLEGAL_ARG_STATUS if statement
work correctly. Also removes needless double conversion

Fixes: 182788325
Test: Launch OboeTester, run "TEST OUTPUT" with MMAP checked
Change-Id: I3d441645bee735c58b0c7c234032ec76a238928d
1 file changed