KVM: arm64: Set ESR_ELx.IL for injected undefined exceptions at EL2

KVM: arm64: Set ESR_ELx.IL for injected undefined exceptions at EL2

inject_undef64() constructs an ESR with EC=0 (Unknown) but does not set
IL. The architecture mandates IL=1 for EC=0 unconditionally (ARM DDI
0487, ESR_ELx.IL description), so the injected syndrome is one that
conforming hardware cannot produce.

Set ESR_ELx_IL in the constructed syndrome.

Fixes: e5d40a5a97c1 ("KVM: arm64: pkvm: Add a generic synchronous exception injection primitive")
Reported-by: sashiko <sashiko@sashiko.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260618121643.4105064-2-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>