This is a first cut at making the AT91 code use the generic GPIO calls.

Note that the original AT91 GPIO calls merged the "mux pin as GPIO" and "set
GPIO direction" functionality into one API call, contrary to what's specified
as a cross-platform portable model.  So this involved a few non-inlinable
functions.

[akpm@osdl.org: cleanups]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>