Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

libefivar: define MDE_CPU_RISCV64

The necessary definitions from EDK2 are present, so this allows the
library to be built on RISC-V.

Regularize the Netflix copyright

Use recent best practices for Copyright form at the top of
the license:
1. Remove all the All Rights Reserved clauses on our stuff. Where we
piggybacked others, use a separate line to make things clear.
2. Use "Netflix, Inc." everywhere.
3. Use a single line for the copyright for grep friendliness.
4. Use date ranges in all places for our stuff.

Approved by: Netflix Legal (who gave me the form), adrian@ (pmc files)

libefivar: use standard 2-Clause FreeBSD license

Approved by: imp
Sponsored by: The FreeBSD Foundation

Bring in EDK2 routines for printing and parsing device paths.

This commit implements the (mostly?) Linux compatible
efidp_format_device_path and efidp_parse_device_path APIs. These are
the only APIs exposed through this library. However, they are built on
code from Tianocore's EDK2 MdePkg. They are brought in as new files
here for reasons described in FreeBSD-update.

Symbol versioning will be introduced to control what's exported from
the EDK2 code.

Some structural changes may be necessary when we move to sharing with
sys/boot/efi.

Sponsored by: Netflix