x86/nvmx: update exit bitmap when using virtual interrupt delivery

x86/nvmx: update exit bitmap when using virtual interrupt delivery

Force an update of the EOI exit bitmap in nvmx_update_apicv, because
the one performed in vmx_intr_assist might not be reached if the
interrupt is intercepted by nvmx_intr_intercept returning true.

Extract the code to update the exit bitmap from vmx_intr_assist into a
helper and use it in nvmx_update_apicv.

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