Revert "shader: on GLES most image formats always require the specification of ro/wo"

This reverts commit 3e7a6ac4e7.

This broke piglit ./bin/arb_shader_image_load_store-semantics

src/vrend_shader.c

@@ -4319,9 +4319,7 @@ static void *emit_image_decl(const struct dump_ctx *ctx, char *glsl_hdr,
 
    if (!image->decl.Writable)
       access = "readonly ";
-   else if ((image->decl.Format != PIPE_FORMAT_R32_FLOAT) &&
-            (image->decl.Format != PIPE_FORMAT_R32_SINT) &&
-            (image->decl.Format != PIPE_FORMAT_R32_UINT))
+   else if (!image->decl.Format)
       access = "writeonly ";
 
    if (ctx->cfg->use_gles) { /* TODO: enable on OpenGL 4.2 and up also */