Remove MAX17135 PMIC support

Support for MAX17135 PMIC was already comment out; as it's not a
component installed in the WaRP board remove it completely.

Signed-off-by: Diego Rondini <diego.rondini@kynetics.it>
Configure I2C1 pads for WaRP

Configure I2C1 pads for WaRP which are used by PMIC.

Signed-off-by: Jacob Postman <jacob@revolution-robotics.com>
Hooked in MAX77696 PMIC driver

Hook PMIC driver to enable MAX77696 driver features. At the moment
driver initialization is called via board_init_max77696() in
mx6sl_pmic_max77696.c; this might be moved, together with associated
pdata struct, to board-mx6sl_warp.c in future. Some additional
configuration might be needed to use IRQ.

Signed-off-by: Jacob Postman <jacob@revolution-robotics.com>