KVM: arm64: Set IL in fake ESR for pKVM memory sharing exit

KVM: arm64: Set IL in fake ESR for pKVM memory sharing exit

__pkvm_memshare_page_req() constructs a fake DABT ESR_EL2 to exit to
the host without setting IL. The ESR has ISV=0, so IL must be 1 per the
architecture. The host does not read IL on this path, but the
constructed syndrome should still be architecturally valid.

Set ESR_ELx_IL.

Fixes: 03313efed5e2 ("KVM: arm64: Implement the MEM_SHARE hypercall for protected VMs")
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260618121643.4105064-8-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>