m68knommu: fix sparse warnings in signal code

m68knommu: fix sparse warnings in signal code

Commit 858b810bf63f ("m68knommu: switch to using asm-generic/uaccess.h")
cleaned up a number of sparse warnings associated with lack of __user
annotations. It also uncovered a couple of more in the signal handling
code:

arch/m68k/kernel/signal.c:923:16:    expected char [noderef] __user *__x
arch/m68k/kernel/signal.c:923:16:    got void *
arch/m68k/kernel/signal.c:1007:16: warning: incorrect type in initializer (different address spaces)
arch/m68k/kernel/signal.c:1007:16:    expected char [noderef] __user *__x
arch/m68k/kernel/signal.c:1007:16:    got void *
arch/m68k/kernel/signal.c:1132:6: warning: symbol 'do_notify_resume' was not declared. Should it be static?

These are specific to a non-MMU configuration. Fix these inserting the
correct __user annotations as required.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>