frontends/omx: use pipe buffer map instead of texture map

Fixes: eb74f9776 ("gallium: split transfer_(un)map into buffer_(un)map and texture_(un)map")

Signed-off-by: Boyuan Zhang <boyuan.zhang@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11233>
3 files changed