avcenc: Remove a leftover define

This should have been removed as part of f5af6314db, but
the second __arm__ define was introduced after the original commit
was written, and not removing the second one was an oversight in
rebasing the patch on top of the new code.

Change-Id: Iccf08ffdef130446dd6e97dc1e15e6a1d4f9386f
1 file changed