genirq: Show irq name in non-oneshot error message

Requesting a threaded IRQ with handler=NULL and !ONESHOT fails, but the
error message does not include the IRQ line name, which makes it harder to
find the offending driver.

Print the IRQ line name to clarify where the error comes from. Use the same
format as the other pr_err() above in the same function.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191105140854.27893-1-luca@lucaceresoli.net