ANDROID: KVM: arm64: Fix repainting of PSCI SYSTEM_RESET2 calls

If the host issues a PSCI SYSTEM_RESET2 call requesting a warm reset
while guest pages are live in the system, then pKVM attempts to convert
this to a cold PSCI SYSTEM_RESET request to ensure the EL3 will clear
memory on the next boot. However, this logic is quite badly broken and
will instead attempt to take the 'mem_protect_lock' spinlock twice which
results in a deadlock.

Fix the repainting so that the 'host_ctxt' is updated inline and we
forward the updated request directly to EL3.

Signed-off-by: Will Deacon <will@kernel.org>
Bug: 259523340
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I44719466b7f5abddf73730a3b74db13f935f92ec