Prefix all internal functions and variables with atmel_ instead of
at91_.

The at91_register_uart_fns() stuff is left as is since I can't find
any actual users of it.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>