__gu_val is const if the passed ptr is const, giving:

  include/linux/pagemap.h: In function 'fault_in_pages_readable':
  include/linux/pagemap.h:442:2: error: assignment of read-only variable '__gu_val'
  include/linux/pagemap.h:448:4: error: assignment of read-only variable '__gu_val'
  include/linux/pagemap.h: In function 'fault_in_multipages_readable':
  include/linux/pagemap.h:499:3: error: assignment of read-only variable '__gu_val'
  include/linux/pagemap.h:508:3: error: assignment of read-only variable '__gu_val'
  make[4]: *** [init/main.o] Error 1

As we don't care about the actual value of __gu_val in the unhandled
case (it will cause a link error anyway), just remove the assignment.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>