broadcom/compiler: disallow TMU spills if max tmu spills is 0

If we are compiling with a strategy that does not allow TMU spills
we should not allow spilling anything that is not a uniform.
Otherwise the RA cost/benefit algorithm may choose to spill a
temp that is not uniform and that will cause us to immediately
fail the strategy and fallback to the next one, even if we
could've instead chosen to spill more uniforms to compile the
program successfully with that strategy.

Some relevant shader-db stats:

total instructions in shared programs: 13040711 -> 13043585 (0.02%)
instructions in affected programs: 234238 -> 237112 (1.23%)
helped: 73
HURT: 172

total threads in shared programs: 415664 -> 415860 (0.05%)
threads in affected programs: 196 -> 392 (100.00%)
helped: 98
HURT: 0

total uniforms in shared programs: 3717266 -> 3721953 (0.13%)
uniforms in affected programs: 12831 -> 17518 (36.53%)
helped: 6
HURT: 100

total max-temps in shared programs: 2174177 -> 2173431 (-0.03%)
max-temps in affected programs: 4597 -> 3851 (-16.23%)
helped: 79
HURT: 21

total spills in shared programs: 4010 -> 4005 (-0.12%)
spills in affected programs: 55 -> 50 (-9.09%)
helped: 5
HURT: 0

total fills in shared programs: 5820 -> 5801 (-0.33%)
fills in affected programs: 186 -> 167 (-10.22%)
helped: 5
HURT: 0

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15168>

src/broadcom/compiler/vir_register_allocate.c

@@ -126,7 +126,8 @@ v3d_choose_spill_node(struct v3d_compile *c,
                          * starting output writes.
                          */
                         bool no_spilling =
-                                c->threads > 1 && started_last_seg;
+                                (c->threads > 1 && started_last_seg) ||
+                                (c->max_tmu_spills == 0);
 
                         /* Discourage spilling of TMU operations */
                         for (int i = 0; i < vir_get_nsrc(inst); i++) {