Don't use critical section when calling intr_irq_handler()

[trasz]

Summary

Don't use critical section when calling intr_irq_handler() - that
function enters critical section by itself anyway.

(XXX: Probably the critical section here can disappear entirely;
I'd rather do that later.)

[trasz]

Fix copy/paste error.

[jhb]

sys/riscv/riscv/intr_machdep.c

174 ↗

(On Diff #77941)

This is likely needed as it is what sets the boundary as to when a context switch to a taskqueue or other there scheduled by a handler executes. If intr_isrc_dispatch() has its own critical section, then you can remove this, but if it doesn't, you probably need to leave this in place.