Convert core 8xx drivers to use in_xxxbe/in_xxx macros instead of direct
memory references.

Other than making IO accesses explicit (which is a plus for readability), a
common set of macros provides a unified place for the volatile flag to
constraint compiler code reordering.

There are several unlucky places at the moment which lack the volatile
flag.
Signed-off-by: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>