ANDROID: KVM: arm64: speacialize and move __activate_traps_hcrx out of __activate_traps_common

In future patches, this function isn't going to be used for
protected VMs. Therefore, move it out of the common function so
that in can be selectively called in future patches.

Moreover, it's behavior betwen VHE and nVHE is going to diverge.

No functional change intended.

Bug: 278749606
Change-Id: I583f5af74edf93a52c2d0328421ed68c7072d507
Signed-off-by: Fuad Tabba <tabba@google.com>