sh: irq: Use seq_put_decimal_ull_width() for decimal values

On a system with n CPUs and m interrupts, there will be n*m decimal
values yielded via seq_printf(.."%10u "..) which has significant costs
parsing format string and is less efficient than seq_put_decimal_ull_width().
Stress reading /proc/interrupts indicates ~30% performance improvement with
this patch.

Signed-off-by: David Wang <00107082@163.com>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>