gpio: max732x driver

This adds a driver supporting a family of I2C port expanders from Maxim,
which includes the MAX7319 and MAX7320-7327 chips.

[[email protected]: minor fixes]
Signed-off-by: Jack Ren <[email protected]>
Signed-off-by: Eric Miao <[email protected]>
Acked-by: Jean Delvare <[email protected]>
Signed-off-by: David Brownell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
4 files changed