x86: fix typo in recent find_vma_prev purge

It turns out that test-compiling this file on x86-64 doesn't really
help, because much of it is x86-32-specific.  And so I hadn't noticed
the slightly over-eager removal of the 'r' from 'addr' variable despite
thinking I had tested it.
Signed-off-by: NLinus "oopsie" Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/hugetlbpage.c

@@ -333,7 +333,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 		 * Lookup failure means no vma is above this address,
 		 * i.e. return with success:
 		 */
-		vma = find_vma(mm, add);
+		vma = find_vma(mm, addr);
 		if (!vma)
 			return addr;