ftrace/recordmcount: Remove duplicate code to find mcount symbol

The code in sift_rel_mcount() and nop_mcount() to get the mcount symbol
number is identical. Replace the two locations with a call to a function
that does the work.

Cc: John Reiser <jreiser@bitwagon.com>
Link: http://lkml.kernel.org/r/20110421023739.488093407@goodmis.org


Signed-off-by: Steven Rostedt <rostedt@goodmis.org>