frontends/va: use un-padded width/height in ExportSurfaceHandle

frontends/va: use un-padded width/height in ExportSurfaceHandle

Issue: VADRMPRIMESurfaceDescriptor width and height are rounded up to
macroblock size (16).

Rootcause: surf->buffer's width/height are rounded up to macroblock size (16),
so they shouldn't be used here.

Fix: Using surf->templ's width/height instead fixes incorrect surface
dimensions being sent via VADRMPRIMESurfaceDescriptor.

Signed-off-by: Krunal Patel <krunalkumarmukeshkumar.patel@amd.corp-partner.google.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14313>