staging: unisys: Remove appos_subsystems.h

Get rid of common-spar/include/diagnostics/appos_subsystems.h.

No one is using it.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>