net sched actions: avoid bitwise operation on signed value in pedit

Since char can be unsigned or signed, and bitwise operators may have
implementation-dependent results when performed on signed operands,
declare 'u8 *' operand instead.

Suggested-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Roman Mashak <mrv@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>