power: pmic: Let PFUZE3000 see all 256 registers

The PFUZE3000 uses registers addresses up to 0xff.

The DM pfuze100 driver supports both pfuze100 and pfuze3000.  Allow it
to use the device type to return the correct number of registers.

Also rename the too generic PMIC_NUM_OF_REGS enumeration value for
pfuze3000 to match the other "PFUZE3000_" prefixed enumerations and the
pfuze100 enumeration value PFUZE100_NUM_OF_REGS.

Cc: Peng Fan <Peng.Fan@freescale.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Trent Piepho <tpiepho@impinj.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>