bus: mhi: Use bitfield operations for handling DWORDs of ring elements

Instead of using the hardcoded bits in DWORD definitions, let's use the
bitfield operations to make it more clear how the DWORDs are structured.

Suggested-by: Alex Elder <elder@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220301160308.107452-7-manivannan.sadhasivam@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>