build: Don't use vpath makefile directive.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Move code centered around specific hardware devices to src/hw/

Move many C files from the src/ directory to the new src/hw/ directory.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Move code cenetered around firmware initialization to src/fw/

Move many C files from the src/ directory to the new src/fw/ directory.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
build: Reorder makefile source list to group like files together.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>