gallium: add PIPE_CAP_TGSI_PACK_HALF_FLOAT to indicate UP2H/PK2H support

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
16 files changed