radv: ensure export arguments are always float

So that the signature is correct and consistent, the inputs to a export
intrinsic should always be 32-bit floats.

This and the previous commit fixes a large amount crashes from
dEQP-VK.spirv_assembly.instruction.graphics.16bit_storage.input_output_int_*
tests

Fixes: b722b29f10 ('radv: add support for 16bit input/output')
Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/amd/vulkan/radv_nir_to_llvm.c

@@ -2571,12 +2571,8 @@ si_llvm_init_export_args(struct radv_shader_context *ctx,
 	} else
 		memcpy(&args->out[0], values, sizeof(values[0]) * 4);
 
-	for (unsigned i = 0; i < 4; ++i) {
-		if (!(args->enabled_channels & (1 << i)))
-			continue;
-
+	for (unsigned i = 0; i < 4; ++i)
 		args->out[i] = ac_to_float(&ctx->ac, args->out[i]);
-	}
 }
 
 static void