mm/zswap: delete unnecessary check before calling free_percpu()

free_percpu() tests whether its argument is NULL and then returns
immediately.  Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zswap.c

@@ -152,8 +152,7 @@ static int __init zswap_comp_init(void)
 static void __init zswap_comp_exit(void)
 {
 	/* free percpu transforms */
-	if (zswap_comp_pcpu_tfms)
-		free_percpu(zswap_comp_pcpu_tfms);
+	free_percpu(zswap_comp_pcpu_tfms);
 }
 
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