anv: fix transform feedback surface size

Non multiple 4 sizes are causing issue in particular < 4.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3450
Fixes: 36ee2fd61c8f ("anv: Implement the basic form of VK_EXT_transform_feedback")
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6430>