staging/sep: Fix printk format warning

This patch fixes gcc's complaints about the wrong format string for
size_t arguments:
"format '%x' expects type 'unsigned int', but argument has type
'size_t'"

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>