ac: fix image load store for GLSL_SAMPLER_DIM_3D

Fixes the following piglit tests:

arb_shader_image_load_store/layer/image3d/layered binding test
arb_shader_image_load_store/max-size/image3d max size test/2048x8x8x1
arb_shader_image_load_store/max-size/image3d max size test/8x2048x8x1
arb_shader_image_load_store/max-size/image3d max size test/8x8x2048x1
arb_shader_image_load_store/semantics/imageload/vertex shader/rgba32f/image3d test

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/amd/common/ac_nir_to_llvm.c

 	} else {
 		bool is_da = glsl_sampler_type_is_array(type) ||
 			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_CUBE ||
+			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_3D ||
 			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_SUBPASS ||
 			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_SUBPASS_MS;
 		LLVMValueRef da = is_da ? ctx->ac.i1true : ctx->ac.i1false;
 				   params, 6, 0);
 	} else {
 		bool is_da = glsl_sampler_type_is_array(type) ||
-			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_CUBE;
+			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_CUBE ||
+			     glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_3D;
 		LLVMValueRef da = is_da ? ctx->ac.i1true : ctx->ac.i1false;
 		LLVMValueRef slc = ctx->ac.i1false;