BACKPORT: tee: optee: fix header dependencies

The optee driver includes the header files in an unusual order,
with asm/pgtable.h before the linux/*.h headers. For some reason
this seems to trigger a build failure:

drivers/tee/optee/call.c: In function 'optee_fill_pages_list':
include/asm-generic/memory_model.h:64:14: error: implicit declaration of function 'page_to_section'; did you mean '__nr_to_section'? [-Werror=implicit-function-declaration]
  int __sec = page_to_section(__pg);   \
drivers/tee/optee/call.c:494:15: note: in expansion of macro 'page_to_phys'
  optee_page = page_to_phys(*pages) +

Let's just include linux/mm.h, which will then get the other
header implicitly.

Change-Id: I01a0a0cab15f132c9e0972a6b65bbdb08487fb82
Fixes: 3bb48ba5cd ("tee: optee: add page list manipulation functions")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
(cherry picked from commit f681e08f67)
Signed-off-by: Victor Chong <victor.chong@linaro.org>

drivers/tee/optee/call.c

@@ -11,11 +11,11 @@
  * GNU General Public License for more details.
  *
  */
-#include <asm/pgtable.h>
 #include <linux/arm-smccc.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/tee_drv.h>
 #include <linux/types.h>