In order to convert the MTU timer to work with sparse IRQ we need
to pass the IRQ used when initializing instead of just letting
it rely on a special name being used in the IRQ header file.

Cc: Alessandro Rubini <rubini@unipv.it>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>