Simplify the error checking in one branch of trap_pfault() and update the nearby comment.
Simplify the error checking in one branch of trap_pfault() and update
the nearby comment.

Correct the style of two return statements in trap_pfault().

Merge a comment from amd64's trap_pfault().

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase