[PATCH 02/09, nds32] Committed: Move ISR impelentation to nds32-isr.c module.

[Chung-Ju Wu]

Hi,

There are many helper functions implemented in nds32.c to
deal with interrupt service routine code generation.
We move all of them into nds32-isr.c module.

Committed as Rev.212281.
  https://gcc.gnu.org/r212281


Best regards,
jasonwucj