Revert "ART: Reference.getReferent intrinsic for arm and arm64"

Reverting because GenerateCalleeMethodStaticOrDirectCall()
prevents replacing kDexCacheViaMethod with kRuntimeCall
where we would not retrieve the target method at all and
leave the runtime to retrieve and call it just like for
unresolved methods.

The intrinsic should be re-implemented by loading the
flags through HLoadClass.

Note that the intrinsic was unimplemented for CC and a bit
broken for non-CC, using LDR instead of LDRB for loading
the flags.

Test: Rely on TreeHugger.
Bug: 32535355
Bug: 30627598

This reverts commit d8c052ac.

Change-Id: I81fd14dac60c94ac543e336f4f3c888259fc8bd7