freedreno/ir3: fix fallout of extra assert

Fixes the following crash that happened after d6110d4d

The problem happens if we first compile a "vanilla" shader with nothing
lowered in NIR, which perform the final lowering passes on so->shader->
nir (including nir_lower_locals_to_regs()), and then later we have
compile a shader with some lowering.  The second time through we would
have already done nir_lower_locals_to_regs().

Arguably this was already a bug, just one we hadn't noticed yet.

Fixes: d6110d4d54 intel/compiler: move nir_lower_bool_to_int32 before nir_lower_locals_to_regs
Signed-off-by: Rob Clark <robdclark@gmail.com>

src/freedreno/ir3/ir3_context.c

@@ -71,7 +71,7 @@ ir3_context_init(struct ir3_compiler *compiler,
 		ctx->s = ir3_optimize_nir(so->shader, s, &so->key);
 	} else {
 		/* fast-path for shader key that lowers nothing in NIR: */
-		ctx->s = so->shader->nir;
+		ctx->s = nir_shader_clone(ctx, so->shader->nir);
 	}
 
 	/* this needs to be the last pass run, so do this here instead of