MIPS: cevt-r4k: Don't call get_c0_compare_int if timer irq is installed

This avoids warning:

[    0.118053] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283

Caused by get_c0_compare_int on secondary CPU.

We also skipped saving IRQ number to struct clock_event_device *cd as
it's never used by clockevent core, as per comments it's only meant
for "non CPU local devices".

Reported-by: Serge Semin <fancer.lancer@gmail.com>
Closes: https://lore.kernel.org/linux-mips/6szkkqxpsw26zajwysdrwplpjvhl5abpnmxgu2xuj3dkzjnvsf@4daqrz4mf44k/


Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>