m68k: Add shared bit to Coldfire kernel page entries

We had problems accessing our NOR flash trough mtd. The system always got
stuck at attaching UBI using ubiattach if booted from NFS or after mounting
squashfs as rootfs directly from NOR flash.
After some testing of the new changes introduced from v3.2-rc1 to v3.2-rc7
we had to apply the following patch to get mtd working again.

[gerg: The problem was ultimately caused by allocated kernel pages not having
the shared (SG) bit set. Without the SG bit set the MMU will look for page
matches incorporating the ASID as well. Things like module regions allocated
using vmalloc would fault when other processes run. ]

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>