[PATCH] airo.c/airo_cs.c: correct prototypes

This patch creates a file airo.h containing prototypes of the global
functions in airo.c used by airo_cs.c .

If you got strange problems with either airo_cs devices or in any other
completely unrelated part of the kernel shortly or long after a airo_cs
device was detected by the kernel, this might have been caused by the
fact that caller and callee disagreed regarding the size of the first
argument to init_airo_card()...

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>