module: fix sprintf format specifier in param_get_byte()

In param_get_byte(), to which the macro STANDARD_PARAM_DEF(byte, ...) expands,
"%c" is used to print an unsigned char. So it gets printed as a character what
is not intended here. Use "%hhu" instead.

[Rusty: note drivers which would be effected:
 drivers/net/wireless/cw1200/main.c
 drivers/ntb/ntb_transport.c:68
 drivers/scsi/lpfc/lpfc_attr.c
 drivers/usb/atm/speedtch.c
 drivers/usb/gadget/g_ffs.c
]

Acked-by: Jon Mason <jon.mason@intel.com> (for ntb)
Acked-by: Michal Nazarewicz <mina86@mina86.com> (for g_ffs.c)
Signed-off-by: Christoph Jaeger <christophjaeger@linux.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>