virgl: obtain supported number of shader sampler views from host

virgl: obtain supported number of shader sampler views from host

Modern games may use more than 16 sampler views, so get what the host
actually supports, and default to 16 on old hosts that don't pass the
value.

Since the possible maximal value of PIPE_MAX_SHADER_SAMPLER_VIEWS doesn't
fit into an uint32_t remove the binding flags, they were only used for
releasing the sampler views, and this can be achieved differently.

v2: Fix compilation error

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: John Bates <jbates@chromium.org> (v1)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13646>