leds: provide helper to register "leds-gpio" devices

leds: provide helper to register "leds-gpio" devices

This function makes a deep copy of the platform data to allow it to live
in init memory.  For a kernel that supports several machines and so
includes the definition for several leds-gpio devices this saves quite
some memory because all but one definition can be free'd after boot.

As the function is used by arch code it must be builtin and so cannot go
into leds-gpio.c.

[[email protected]: s/CONFIG_LED_REGISTER_GPIO/CONFIG_LEDS_REGISTER_GPIO/]
Signed-off-by: Uwe Kleine-König  <[email protected]>
Cc: Russell King <[email protected]>
Acked-by: Richard Purdie <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Sascha Hauer <[email protected]>
Tested-by: H Hartley Sweeten <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>