x86/uv/nmi, kgdb/kdb: Fix UV NMI handler when KDB not configured

x86/uv/nmi, kgdb/kdb: Fix UV NMI handler when KDB not configured

Fix UV call into kgdb to depend only on whether KGDB is defined
and not both KGDB and KDB.  This allows the power nmi command to
use the gdb remote connection if enabled.  Note new action of
'kgdb' needs to be set as well to indicate user wants to wait
for gdb to be connected.  If it's set to 'kdb' then an error
message is displayed if KDB is not configured.

Also note that if both KGDB and KDB are enabled, then the action
of 'kgdb' or 'kdb' has no affect on which is used.  See the KGDB
documentation for further information.

Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Hedi Berriche <hedi@sgi.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Link: http://lkml.kernel.org/r/20140114162551.635540667@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>