staging: speakup: fix printk format warning

Fix printk format warning:

drivers/staging/speakup/serialio.c:44: warning: format '%x' expects type 'unsigned int', but argument 2 has type 'long unsigned int'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: <speakup@braille.uwo.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>