regulator: Remove unneeded include of linux/delay.h from regulator drivers

All the drivers that need delay for the regulator voltage output voltage to
stabilize after being enabled or after being set to a new value has been
converted to implement enable_time and set_voltage_time_sel callbacks.
Then regulator core will take care of the necessary delay.

For the drivers that don't need the delay, don't need to include linux/delay.h.
This patch removes the unneeded include of linux/delay.h in regulator drivers.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>