freedreno/a6xx: Allow blit based transfers

Some apps (like firefox and chromium) seem to like to create textures
with internal format GL_RGBA8 but then upload GL_BGRA to them.  If the
app were a bit more clever it could hit the memcpy path.  But fallback
sw conversion (convert_ubytes()) is slow.  If we are going to have to
make this extra copy, do it on the gpu.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30064>

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -278,6 +278,10 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
       return has_compute(screen);
 
    case PIPE_CAP_TEXTURE_TRANSFER_MODES:
+      if (screen->gen >= 6)
+         return PIPE_TEXTURE_TRANSFER_BLIT;
+      return 0;
+
    case PIPE_CAP_PCI_GROUP:
    case PIPE_CAP_PCI_BUS:
    case PIPE_CAP_PCI_DEVICE: