synclink_gt: add compat_ioctl

Add support for 32 bit ioctl on 64 bit systems for synclink_gt

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>