accel/ivpu: pages_use_count is now a refcount_t

Commit 051b6646d36d ("drm/shmem-helper: Use refcount_t for
pages_use_count") changed the type of
drm_gem_shmem_object::pages_use_count but accel drivers were left
behind.

Fixes: 051b6646d36d ("drm/shmem-helper: Use refcount_t for pages_use_count")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Cc: Maciej Falkowski <maciej.falkowski@linux.intel.com>
Cc: Oded Gabbay <ogabbay@kernel.org>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250327104300.1982058-1-boris.brezillon@collabora.com