sh: Delete unnecessary checks before the function call "mempool_destroy"

The mempool_destroy() function tests whether its argument is NULL
and then returns immediately. Thus the test around the calls is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Rich Felker <dalias@libc.org>

arch/sh/kernel/dwarf.c

@@ -1009,10 +1009,8 @@ static void __init dwarf_unwinder_cleanup(void)
 	rbtree_postorder_for_each_entry_safe(cie, next_cie, &cie_root, node)
 		kfree(cie);
 
-	if (dwarf_reg_pool)
-		mempool_destroy(dwarf_reg_pool);
-	if (dwarf_frame_pool)
-		mempool_destroy(dwarf_frame_pool);
+	mempool_destroy(dwarf_reg_pool);
+	mempool_destroy(dwarf_frame_pool);
 	kmem_cache_destroy(dwarf_reg_cachep);
 	kmem_cache_destroy(dwarf_frame_cachep);
 }