powerpc: Add ioctls for RS485 mode control of serial drivers

These ioctls take a struct serial_rs485
(see linux/serial.h) as argument. They are already available
on x86. This patch adds them for the powerpc architecture.
Signed-off-by: Matthias Fuchs <mfuchs@ma-fu.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/ioctls.h

@@ -89,6 +89,8 @@
 #define TIOCSBRK	0x5427  /* BSD compatibility */
 #define TIOCCBRK	0x5428  /* BSD compatibility */
 #define TIOCGSID	0x5429  /* Return the session ID of FD */
+#define TIOCGRS485	0x542e
+#define TIOCSRS485	0x542f
 #define TIOCGPTN	_IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
 #define TIOCSPTLCK	_IOW('T',0x31, int)  /* Lock/unlock Pty */