Introduce PcdXenGrantFrames to replace a define in XenBusDxe and allow
the same value to be used in a different module.
The reason for the number of page to be 4 doesn't exist anymore, so
simply remove the comment.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190813113119.14804-33-anthony.perard@citrix.com>