Move MI bits of efirt to a MI file

[andrew]

Summary

To prepare for adding EFI runtime services support on arm64 move the
machine independent parts of the existing code to a new file that can
be shared between the two architectures.

Test Plan

I've tested on arm64, but don't have an amd64 test machine so haven't tested there.

[kib]

So the 1:1 mapping trick is becoming the arch requirement to support RT ?

sys/kern/subr_efi.c

68

Why is this in MD file ?

[andrew]

• Move the locking macros to a MD header
• Ddd subr_efi.c to the module Makefile

[andrew]

I left the name as it all architectures that currently support EFI RT use a 1:1 map.

[kib]

May be add sys/dev/efirt and move subr_efi.c there ? EFI is not a generic facility, it is MD, just that it exists on both x86 and arm64.

[imp]

My eye didn't trip over anything...

[andrew]

Move the MI file under sys/dev/efidev

[imp]

I like this layout better...