regulator: max8660 - fix a memory leak in max8660_remove()

In max8660_probe(), we allocate memory for max660.
In max8660_remove(), current implementation only free rdev
which is a member of struct max8660.
Thus, there is a small memory leak when we unload the module.

This patch fixes the memory leak by passing max660 to i2c clientdata,
and properly kfree(max8660) in max8660_remove().

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>