count: Include atomic_nehalem.pdf instead of atomic_nehalem.png

Without any suffix specified, \includegraphics{} prefers .png to .pdf
by default.

Fixes: 04e270767c34 ("count: Restore 'fig:count:Atomic Increment Scalability on Nehalem'")
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

count/count.tex

diff --git a/count/count.tex b/count/count.tex
index 6fd54b5..bdbc4cd 100644
--- a/count/count.tex
+++ b/count/count.tex
@@ -248,7 +248,7 @@
 
 \begin{figure}[tb]
 \centering
-\resizebox{2.5in}{!}{\includegraphics{CodeSamples/count/atomic_nehalem}}
+\resizebox{2.5in}{!}{\includegraphics{CodeSamples/count/atomic_nehalem.pdf}}
 \caption{Atomic Increment Scalability on Nehalem}
 \label{fig:count:Atomic Increment Scalability on Nehalem}
 \end{figure}