We need the boot CPU's tvec_bases[] entry to be initialised super-early in
boot, for early_serial_setup().  That runs within setup_arch(), before even
per-cpu areas are initialised.

The patch changes tvec_bases to use compile-time initialisation, and adds a
separate array `tvec_base_done' to keep track of which CPU has had its
tvec_bases[] entry initialised (because we can no longer use the zeroness of
that tvec_bases[] entry to determine whether it has been initialised).

Thanks to Eugene Surovegin <ebs@ebshome.net> for diagnosing this.

Cc: Eugene Surovegin <ebs@ebshome.net>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>