Revert "etnaviv: Cannot render to rb-swapped formats"

This reverts commit 658568941d.

With the help of shader variants we can render to rb-swapped
formats now. Fixes about 60 piglits.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>

src/gallium/drivers/etnaviv/etnaviv_screen.c

@@ -476,11 +476,8 @@ etna_screen_is_format_supported(struct pipe_screen *pscreen,
       return FALSE;
 
    if (usage & PIPE_BIND_RENDER_TARGET) {
-      /* If render target, must be RS-supported format that is not rb swapped.
-       * Exposing rb swapped (or other swizzled) formats for rendering would
-       * involve swizzing in the pixel shader.
-       */
-      if (translate_rs_format(format) != ETNA_NO_MATCH && !translate_rs_format_rb_swap(format)) {
+      /* if render target, must be RS-supported format */
+      if (translate_rs_format(format) != ETNA_NO_MATCH) {
          /* Validate MSAA; number of samples must be allowed, and render target
           * must have MSAA'able format. */
          if (sample_count > 1) {