[media] siano: apply debug flag to module level

Siano modules already had sms_dbg flag which is a module parameter which
sets the debug mode so module prints messages to dmesg for debugging.
The variable was static therefore apply only to the file which defines
the module. In modules as smsmdtv.ko that contain a few files, the debug
flag applied only for functions in that main file.
flag was changed to be non-static and therefore can be accessed by all
module files (although it is still not exported out of the module).

Signed-off-by: Doron Cohen <doronc@siano-ms.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>