x86/vvmx: fix VM_EXIT_ACK_INTR_ON_EXIT handling

x86/vvmx: fix VM_EXIT_ACK_INTR_ON_EXIT handling

When VM_EXIT_ACK_INTR_ON_EXIT is clear in the vmexit control vmcs
register the bit 31 of VM_EXIT_INTR_INFO must be 0, in order to denote
that the field doesn't contain any interrupt information. This is not
currently acknowledged as the field always get filled with valid
interrupt information, regardless of whether VM_EXIT_ACK_INTR_ON_EXIT
is set.

Fix this and only fill VM_EXIT_INTR_INFO when VM_EXIT_ACK_INTR_ON_EXIT
is set. Note that this requires one minor change in
nvmx_update_apicv in order to obtain the interrupt information from
the internal state rather than the nested vmcs register.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>