layerscape: fix felix DSA driver compilation

layerscape: fix felix DSA driver compilation

It isn't used at the moment but let's fix it anyway.

This fixes:
  CC      drivers/net/dsa/ocelot/felix.o
drivers/net/dsa/ocelot/felix.c:646:22: error: initialization of 'enum dsa_tag_protocol (*)(struct dsa_switch *, int,  enum dsa_tag_protocol)' from incompatible pointer type 'enum dsa_tag_protocol (*)(struct dsa_switch *, int)' [-Werror=incompatible-pointer-types]
  .get_tag_protocol = felix_get_tag_protocol,
                      ^~~~~~~~~~~~~~~~~~~~~~

for users enabling CONFIG_NET_DSA_MSCC_FELIX.

Fixes: 1f5024aa73fc ("kernel: backport b53/bcm_sf2 changes from v5.6")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>