mfd: tps6105x: Remove linux/regulator/driver.h include

This driver makes no use of linux/regulator/driver.h which should only
be used by drivers implementing a regulator.  Since it's unlikely to
ever need anything from there remove the include.

Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>