m68knommu: Remove mm.h include from uaccess_no.h

In file included
  from include/linux/huge_mm.h:8,
  from include/linux/mm.h:567,
  from arch/m68k/include/asm/uaccess_no.h:8,
  from arch/m68k/include/asm/uaccess.h:3,
  from include/linux/uaccess.h:11,
  from include/linux/sched/task.h:11,
  from include/linux/sched/signal.h:9,
  from include/linux/rcuwait.h:6,
  from include/linux/percpu-rwsem.h:7,
  from kernel/locking/percpu-rwsem.c:6:
 include/linux/fs.h:1422:29: error: array type has incomplete element type 'struct percpu_rw_semaphore'
    1422 |  struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];

Removing the include of linux/mm.h from the uaccess header solves the problem
and various build tests of nommu configurations still work.

Fixes: 80fbaf1 ("rcuwait: Add @state argument to rcuwait_wait_event()")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lkml.kernel.org/r/87fte1qzh0.fsf@nanos.tec.linutronix.de

arch/m68k/include/asm/uaccess_no.h

@@ -5,7 +5,6 @@
 /*
  * User space memory access functions
  */
-#include <linux/mm.h>
 #include <linux/string.h>
 
 #include <asm/segment.h>