powerpc/8xx: Revert commit 3eebad840152a356caa448b44a6ae43cc9921ec2

powerpc/8xx: Revert commit 3eebad840152a356caa448b44a6ae43cc9921ec2

The commit 3eebad840152a356caa448b44a6ae43cc9921ec2 ("powerpc/8xx: Fix
regression introduced by cache coherency rewrite") is not needed
anymore.  The issue was because dcbst wrongly sets the store bit when
causing a DTLB error, but this is now fixed by commit
81ccb7c4797e6d4a6ec36fbad71f9b28466e4426 ("powerpc/8xx: Fixup DAR from
buggy dcbX instructions.") which handles the buggy dcbx instructions on
data page faults on the 8xx.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[scottwood@freescale.com: fix commit message]
Signed-off-by: Scott Wood <scottwood@freescale.com>