Revert "KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption"

This reverts commit 468ef153 which is
commit b321c31c upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I5dcbd0a528203c36838c8f1a91d4a9c51be12ea9
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>