uboot-phytec

pmic_fsl: Introduce FSL_PMIC_I2C_LENGTH

Introduce FSL_PMIC_I2C_LENGTH to configure the number of bytes that are used to
communicate with the PMIC via I2C.

Instead of hardcoding the value, pass the number via a configurable option per
PMIC type.

This will be useful for adding support for PMIC MC34704 from Freescale, which
uses only one byte in its I2C protocol.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>