audit: do not call audit_getname on error

Just a code cleanup really.  We don't need to make a function call just for
it to return on error.  This also makes the VFS function even easier to follow
and removes a conditional on a hot path.

Signed-off-by: Eric Paris <eparis@redhat.com>

diff --cc fs/namei.c
Simple merge

diff --cc kernel/auditsc.c
Simple merge