riscv trap_pfault: remove unneeded hold of the process around vm_fault() call.

[kib]

Summary

This is re-appearance of the nop code removed from other arches in r287625.

[markj]

sys/riscv/riscv/trap.c

240

Wasn't this incorrect for faults on pipe_map or exec_map?

[kib]

sys/riscv/riscv/trap.c

240

Incorrect what ? pipe or exec maps are kernel submaps. What do you mean exactly ?

[markj]

sys/riscv/riscv/trap.c

240

Sorry, I meant that the comment seemed incorrect. I don't see why we would lock a process for faults on a user map, but not a fault on pipe_map. Anyway, it is not important.