dcb: app: modify dcb_app_print_filtered() for dcb-rewr reuse

dcb: app: modify dcb_app_print_filtered() for dcb-rewr reuse

Where dcb-app requires protocol to be the printed key, dcb-rewr requires
it to be the priority. Adapt existing dcb-app print functions for this.

dcb_app_print_filtered() has been modified, to take two callbacks; one
for printing the entire string (pid and prio), and one for the pid type
(dec, hex, dscp, pcp). This saves us for making one dedicated function
for each pid type for both app and rewr.

Also, printing the colon is now expected to be handled by the
print_pid_prio() callback.

Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Petr Machata <me@pmachata.org>
Signed-off-by: David Ahern <dsahern@kernel.org>