broadcom/vc5: Increase simulator memory for tex-miplevel-selection.

We were overflowing, because of all the little 4k allocations for CLs that
were getting expanded to 128kb in the simulator due to the GMP alignment.

src/gallium/drivers/vc5/vc5_simulator.c

@@ -676,7 +676,7 @@ vc5_simulator_init_global(void)
         }
 
         sim_state.v3d = v3d_hw_auto_new(NULL);
-        v3d_hw_alloc_mem(sim_state.v3d, 256 * 1024 * 1024);
+        v3d_hw_alloc_mem(sim_state.v3d, 1024 * 1024 * 1024);
         sim_state.mem_base =
                 v3d_hw_get_mem(sim_state.v3d, &sim_state.mem_size,
                                &sim_state.mem);