ARM: footbridge: fix EBSA285 LEDs

commit 67130c5464f50428aea0b4526a6729d61f9a1d53 upstream.

- The LEDs register is write-only: it can't be read-modify-written.
- The LEDs are write-1-for-off not 0.
- The check for the platform was inverted.

Fixes: cf6856d6 ("ARM: mach-footbridge: retire custom LED code")
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>