amd64 EFI RT: provide fault data on call fault

[kib]

Summary

amd64: allow trap_fatal() to be not that fatal

amd64: on any fault during call to EFI RT, restore execution and print fault details

The fault info should be useful to see what specifically BIOS tried to
do and why it faulted.  E.g. it might allow to see which EFI memory
segment needs to be mapped in addition to normal runtime segments, to
work around the fault.

[markj]

sys/amd64/amd64/trap.c

868

It is weird for the function to be called trap_fatal() if it also has a flag determining whether it is fatal.

Maybe keep the trap_fatal() name and panic() call for the common case, and rename the rest of trap_fatal() to trap_diag().

[kib]

Use trap_diag()