ARM64: Encode constants when it is possible.

Small optimization which improves HVecReplicateScalar by encoding
immediates directly into NEON instruction when possible instead of
generating constant in GPR and transferring it into NEON register.

Test: test-art-target, test-art-host.
Change-Id: I2113bbd98c0dc8433d2b7048921b9ed7c35ef1c5
5 files changed