reiserfs: dont use BUG when panicking

Change reiserfs_panic() to use panic() initially instead of BUG().  Using
BUG() ignores the configurable panic behavior, so systems that should be
failing and rebooting are left hanging.  This causes problems in
active/standby HA scenarios.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>