Fix CAS intrinsic to clear exclusive if values don't match.
Fix CAS intrinsic to clear exclusive if values don't match.

The LDREX has a matching STREX if the values match, but it needed
a CLREX for the case where they didn't.

Bug: 10530407
Change-Id: I46b474cca326a251536e7f214c80486694431386
(cherry picked from commit 78765e84a3654357a03f84b76985556cf7d9731a)
treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst