mfd: 88pm860x: Move over to new I2C device .probe() call

As part of an effort to rid the mostly unused second parameter for I2C
related .probe() functions and to conform to other existing frameworks
we're moving over to a temporary replacement .probe() call-back.

Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kieran Bingham <kieran@bingham.xyz>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>