pvr: Use correct pbe format for VK_FORMAT_A8B8G8R8_UNORM_PACK32

pvr: Use correct pbe format for VK_FORMAT_A8B8G8R8_UNORM_PACK32

Fixes:
  - dEQP-VK.api.image_clearing.core.clear_color_image.1d.linear
      .single_layer.a8b8g8r8_unorm_pack32_71x1
  - dEQP-VK.api.image_clearing.core.clear_color_image.2d.linear
      .single_layer.a8b8g8r8_unorm_pack32_33x128

Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Reported-by: Soroush Kashani <soroush.kashani@imgtec.com>
Reviewed-by: Karmjit Mahil <Karmjit.Mahil@imgtec.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23312>