power: regulator: add pfuze100 support

1. Add new regulator driver pfuze100.
   * Introduce struct pfuze100_regulator_desc for maintaining info
     for one regulator.
2. Add new Kconfig entry DM_REGULATOR_PFUZE100 for pfuze100.
3. This driver intends to support PF100, PF200 and PF3000.
4. Add related macro definition in pfuze header file.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Simon Glass <sjg@chromium.org>