leds: add driver for TCA6507 LED controller

leds: add driver for TCA6507 LED controller

TI's TCA6507 is the LED driver in the GTA04 Openmoko motherboard.  The
driver provides full support for brightness levels and hardware blinking.

This driver can drive each of 7 outputs as an LED or a GPIO output,
and provides hardware-assist blinking.

[[email protected]: fix __mod_i2c_device_table alias]
[[email protected]: coding-style fixes]
Signed-off-by: NeilBrown <[email protected]>
Cc: Richard Purdie <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Dan Carpenter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>