cris: fix some build warnings in pinmux.c

Fix some harmless warnings such as

  arch/cris/arch-v32/mach-a3/pinmux.c:273: warning: ISO C90 forbids mixed declarations and code:

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>