i2400m/SDIO: header for the SDIO subdriver

This contains the common function declaration and constants for the
SDIO driver for the 2400m Wireless WiMAX Connection and it's debug
level settings.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>