KVM: arm64: timers: Don't BUG() on unhandled timer trap

KVM: arm64: timers: Don't BUG() on unhandled timer trap

Although not handling a trap is a pretty bad situation to be in,
panicing the kernel isn't useful and provides no valuable
information to help debugging the situation.

Instead, dump the encoding of the unhandled sysreg, and inject
an UNDEF in the guest. At least, this gives a user an opportunity
to report the issue with some information to help debugging it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230112123829.458912-4-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>