panfrost: Implement missing texture formats

 - Implements RGB565/RGBA5551 formats
 - Don't advertise support for flipped RGBA5551 and ETC

Fixes remaining tests in dEQP-GLES2.functional.texture.format.* which is
now at 36/36.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
diff --git a/src/gallium/drivers/panfrost/pan_format.c b/src/gallium/drivers/panfrost/pan_format.c
index cac8a3d..cb1c71f 100644
--- a/src/gallium/drivers/panfrost/pan_format.c
+++ b/src/gallium/drivers/panfrost/pan_format.c
@@ -182,6 +182,18 @@
                 case PIPE_FORMAT_Z32_UNORM:
                         return MALI_Z32_UNORM;
 
+                case PIPE_FORMAT_B5G6R5_UNORM:
+                        return MALI_RGB565;
+
+                case PIPE_FORMAT_B5G5R5A1_UNORM:
+                        return MALI_RGB5_A1_UNORM;
+
+                case PIPE_FORMAT_A1B5G5R5_UNORM:
+                case PIPE_FORMAT_X1B5G5R5_UNORM:
+                        /* Not supported - this is backwards from OpenGL! */
+                        assert(0);
+                        break;
+
                 default:
                         /* Fallthrough to default */
                         break;