uvp/av: complete all processing in pre_create/destroy_av() calls

uvp/av: complete all processing in pre_create/destroy_av() calls

According to the documentation, if a UVP returns IB_VERBS_PROCESSING_DONE
from a pre() IOCTL call, then all verbs related processing has completed.
The mthca pre_create_av() and pre_destroy_av() uvp implementation can
both return IB_VERBS_PROCESSING_DONE, but requires that users still call
post_create_av() and post_destroy_av().  Fix the mthca UVP to complete all
processing in the pre() IOCTL calls when returning IB_VERBS_PROCESSING_DONE,
and update IBAL to remove unnecessary post() IOCTL calls.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
git-svn-id: svn://openib.tc.cornell.edu/gen1/trunk@1442 ad392aa1-c5ef-ae45-8dd8-e69d62a5ef86