MAINTAINERS: Add bug tracking system location entry type

Following the kernel Bugzilla discussion during the Kernel Summit
(https://lwn.net/Articles/705245/), add bug tracking system location
entry type (B) to MAINTAINERS and populate it for several subsystems
known to be using the kernel BZ actively (and add the upstream BZ for
ACPICA too).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>