v3d/compiler: use mask for 16bit and 32bit return values

There are only ever two possibilities here so lets use a mask.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34742>

src/broadcom/compiler/v3d_compiler.h

@@ -408,9 +408,11 @@ static inline uint8_t v3d_slot_get_component(struct v3d_varying_slot slot)
 }
 
 struct v3d_key {
-        struct {
-                uint8_t return_size;
-        } sampler[V3D_MAX_TEXTURE_SAMPLERS];
+        /* Mask of sampler return sizes.
+         * 0 is 16bit
+         * 1 is 32bit
+         */
+        uint32_t sampler_is_32b;
 
         uint8_t ucp_enables;
         bool is_last_geometry_stage;

src/broadcom/compiler/v3d_tex.c

@@ -239,7 +239,7 @@ v3d_vir_emit_tex(struct v3d_compile *c, nir_tex_instr *instr)
          * parameter if the output is 32 bit
          */
         bool output_type_32_bit =
-                c->key->sampler[sampler_idx].return_size == 32;
+                (c->key->sampler_is_32b & (1 << sampler_idx));
 
         struct V3D42_TMU_CONFIG_PARAMETER_0 p0_unpacked = {
         };

src/broadcom/compiler/vir.c

@@ -601,8 +601,8 @@ lower_tex_packing_cb(const nir_tex_instr *tex, const void *data)
    int sampler_index = nir_tex_instr_need_sampler(tex) ?
       tex->sampler_index : tex->backend_flags;
 
-   return c->key->sampler[sampler_index].return_size == 16 ?
-      nir_lower_tex_packing_16 : nir_lower_tex_packing_none;
+   return (c->key->sampler_is_32b & (1 << sampler_index)) ?
+      nir_lower_tex_packing_none : nir_lower_tex_packing_16;
 }
 
 static bool