gallium/aux: include nr_samples in util_resource_size() computation

This function is only used in two places:
1. VMware driver, but only for HUD reporting
2. st/nine state tracker, used for texture memory accounting

Fixes: a69efa94 ("util: add new util_resource_size() function in
u_resource.[ch]")

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Charmaine Lee <charmainel@vmware.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
(cherry picked from commit dde8309c)