mm/hmm: remove redundant variable align_end

Variable align_end is assigned a value but it is never read, so the
variable is redundant and can be removed.  Cleans up the clang warning:
Value stored to 'align_end' is never read

Link: http://lkml.kernel.org/r/20171017143837.23207-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hmm.c

@@ -803,11 +803,10 @@ static RADIX_TREE(hmm_devmem_radix, GFP_KERNEL);
 
 static void hmm_devmem_radix_release(struct resource *resource)
 {
-	resource_size_t key, align_start, align_size, align_end;
+	resource_size_t key, align_start, align_size;
 
 	align_start = resource->start & ~(PA_SECTION_SIZE - 1);
 	align_size = ALIGN(resource_size(resource), PA_SECTION_SIZE);
-	align_end = align_start + align_size - 1;
 
 	mutex_lock(&hmm_devmem_lock);
 	for (key = resource->start;