of_irq_get_byname() may return a negative error number as well as 0 on
failure, while timer_irq_init() only checks for 0, blithely continuing with
the call to request_[percpu_]irq() -- those functions expect *unsigned int*,
so would probably fail anyway when a large IRQ number resulting from a
conversion of a negative error number is passed to them... This, however,
is incorrect behavior -- error number is not IRQ number.
Fileter out the negative error numbers, complain, and return them to the
timer_irq_init()'s callers...[...]
Fixes: dc11bae78529 ("clocksource/drivers: Add timer-of common init routine")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>