armv7a: fix interpretation of MMU table

armv7a: fix interpretation of MMU table

On armv7 there no longer are 1kB pages. Instead the bit that in
older architectures distinguished 1kB pages from 4kB pages is on
armv7 used for as execute-never marker. There may now also be 16MB
supersections with 40 bit physical address.

Change-Id: I959bdb8012782a9d07d968907a21f50e3d9b356a
Signed-off-by: Daniel Glöckner <daniel-gl@gmx.net>
Reviewed-on: http://openocd.zylin.com/2386
Tested-by: jenkins
Reviewed-by: Vladimir Svoboda <ze.vlad@gmail.com>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>