staging: line6: control.c eliminate strict_strtoul() in pod_set_param_int()

Exchange strict_strtoul() with kstrtou8() and make "value" a u8 instead of a
unsigned long. This is also needed for the changed
line6_pod_transmit_parameter().

Signed-off-by: Johannes Thumshirn <morbidrsa@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>