A couple of fixes for interrupt chip drivers:

  - Ensure to skip the clear register space in the MBIGEN driver when
    calculating the node register index. Otherwise the clear register is
    clobbered and the wrong node registers are accessed.

  - Fix a signed/unsigned confusion in the loongarch CPU driver which
    converts an error code to a huge "valid" interrupt number.

  - Convert the mesion GPIO interrupt controller lock to a raw spinlock so
    it works on RT.

  - Add a missing static to a internal function in the pic32 EVIC driver.