[SCSI] fcoe: Move fcoe_debug_logging from fcoe.h to fcoe.c

Move the definition of the global variable fcoe_debug_logging
from fcoe.h to fcoe.c. Avoid that sparse complains about missing
declarations for local functions or variables by declaring these
static.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>