sh64: kernel: remove useless variable 'regs'

Remove useless variable 'regs' to avoid the related warnings (warning is
treated as error).

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>