ARM: Fix SA1100 Neponset serial section mismatch

WARNING: vmlinux.o(.devinit.text+0x524): Section mismatch in reference from the function neponset_probe() to the function .init.text:sa1100_register_uart_fns()
The function __devinit neponset_probe() references
a function __init sa1100_register_uart_fns().
If sa1100_register_uart_fns is only used by neponset_probe then
annotate sa1100_register_uart_fns with a matching annotation.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Sam Ravnborg <sam@ravnborg.org>