m32r: fix 'fix breakage from "m32r: use generic ptrace_resume code"' fallout

Commit acdc0d5e ('m32r: fix breakage from "m32r: use generic
ptrace_resume code"') tried to fix a problem in commit e34112e3
("m32r: use generic ptrace_resume code") by returning values in a
function returning void, causing:

  arch/m32r/kernel/ptrace.c: In function 'user_enable_single_step':
  arch/m32r/kernel/ptrace.c:594:3: warning: 'return' with a value, in function returning void [enabled by default]
  arch/m32r/kernel/ptrace.c:598:3: warning: 'return' with a value, in function returning void [enabled by default]
  arch/m32r/kernel/ptrace.c:601:3: warning: 'return' with a value, in function returning void [enabled by default]
  arch/m32r/kernel/ptrace.c:604:2: warning: 'return' with a value, in function returning void [enabled by default]

Remove the unneeded return values.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>