i2c: add dm_i2c_reg_clrset

Add function to apply a bitmask to an i2c register, so
that specific bits can be cleared and/or set.

Suggested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
3 files changed