rapidio: fix maintenance access to higher memory areas

Fix the maintenance access functions to farend RapidIO devices.
1. Fixed shift of the given offset, to open the maintenance window
2. Mask offset to limit access to the opened maintenance window
3. Added extended destid part to rowtear register, required for 16bit mode

This method is matching maintenance transactions generation described
by Freescale in the appnote AN2932. With this modification full access
to a 16MB maintenance window is possible, this patch is required for
IDT cps switches. For easier handling of the access routines, the
access was limited to aligned memory regions. This should be no problem
because all registers are 32bit wide.

Signed-off-by: Thomas Moll <thomas.moll@sysgo.com>
Tested-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Li Yang <leoli@freescale.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>