i2c: mv_i2c.c: Prepare driver for DM conversion

i2c: mv_i2c.c: Prepare driver for DM conversion

To prepare for the DM conversion, we add a layer of compatibility
functions to be used by both the legacy and the DM functions.

Signed-off-by: Stefan Roese <[email protected]>
Cc: Nadav Haklai <[email protected]>
Cc: Kostya Porotchkin <[email protected]>
Cc: Wilson Ding <[email protected]>
Cc: Victor Gu <[email protected]>
Cc: Hua Jing <[email protected]>
Cc: Terry Zhou <[email protected]>
Cc: Hanna Hawa <[email protected]>
Cc: Haim Boot <[email protected]>
Cc: Heiko Schocher <[email protected]>