As of 1eef5d2f ("ARM: domains: switch to keeping domain value in
register") we no longer need to include asm/domains.h into
asm/thread_info.h.  Remove it.
Tested-by: NRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>