kprobes: support probing module __init function

Allow kprobes to probe module __init routines.  When __init functions are
freed, kprobes which probe those functions are set to "Gone" flag.  These
"Gone" probes are disarmed from the code and never be enabled.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>