[ARM] Feroceon: Feroceon-specific WA-cache compatible {copy,clear}_user_page()

This patch implements a set of Feroceon-specific
{copy,clear}_user_page() routines that perform more optimally than
the generic implementations.  This also deals with write-allocate
caches (Feroceon can run L1 D in WA mode) which otherwise prevents
Linux from booting.

[nico: optimized the code even further]

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Tested-by: Sylver Bruneau <sylver.bruneau@googlemail.com>
Tested-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>