Add support for the on-board voltage regulator hooked up to GPIO3_20
on r8a7779 Marzen. The board schematics describes the regulator as U4
TPS2110A. Input wise, U4 has D0 fixed to ground, D1 tied to GPIO3_20
while IN1 is fixed to 3.3V and IN2 is fixed to 1.8V. OUT goes to the
pull-ups for the data pins of SDHI0.
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>