[MIPS] unexport __kmap_atomic_to_page

This patch removes the no longer used export of __kmap_atomic_to_page.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/highmem.c

@@ -116,4 +116,3 @@ EXPORT_SYMBOL(__kmap);
 EXPORT_SYMBOL(__kunmap);
 EXPORT_SYMBOL(__kmap_atomic);
 EXPORT_SYMBOL(__kunmap_atomic);
-EXPORT_SYMBOL(__kmap_atomic_to_page);