r600: increase number of ubos by one to 14

Ideally we'd support 16 (d3d11 requires 15, and mesa subtracts one for non-ubo
constants), but that's kind of impossible (it would be only doable if either
we'd somehow merge the mesa non-ubo constants with the driver constants, or
only use the driver constants with vtx fetch instead of through the kcache
mechanism - the latter probably wouldn't be too bad).
For now just do as the comment already said, place the gs ring (not really
a const buffer in any case) which is only ever referred to through vc fetch
clauses at index 16. Throw in a couple asserts for good measure to make sure
the hw limit isn't exceeded.

Tested-by: Konstantin Kharlamov <hi-angel@yandex.ru>
Reviewed-by: Dave Airlie <airlied@redhat.com>

src/gallium/drivers/r600/r600_asm.c

@@ -1008,6 +1008,7 @@ static int r600_bytecode_alloc_inst_kcache_lines(struct r600_bytecode *bc,
 			continue;
 
 		bank = alu->src[i].kc_bank;
+		assert(bank < R600_MAX_HW_CONST_BUFFERS);
 		line = (sel-512)>>4;
 		index_mode = alu->src[i].kc_rel ? 1 : 0; // V_SQ_CF_INDEX_0 / V_SQ_CF_INDEX_NONE