pvr: Transfer support flipped rectangle mapping

pvr: Transfer support flipped rectangle mapping

The rectangles in "struct pvr_rect_mapping" are unsigned so a
flipped rectangle mapping isn't possible. Add new struct members
flip_x and flip_y to specify flipped mapping.

Add support for flipped rectangles in transfer copy blit path.
Support for flipped rectangles in the clip blit path is not done
in this change.

The new booleans are false by default because transfer command
"struct pvr_transfer_cmd" is zeroed on allocation in
pvr_transfer_cmd_alloc (pvr_blit.c).

Fixes:
  dEQP test case: dEQP-VK.api.copy_and_blit.core.blit_image.simple_tests
    .mirror_xy.nearest

Signed-off-by: Oskar Rundgren <oskar.rundgren@imgtec.com>
Reviewed-by: Frank Binns <frank.binns@imgtec.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22958>