The MT7530_MFC register is on MT7530, MT7531, and the switch on the MT7988
SoC. Rename it to MT753X_MFC. Bit 7 to 0 differs between MT7530 and
MT7531/MT7988. Add MT7530 prefix to these definitions, and define the
IGMP/MLD Query Frame Flooding Ports mask for MT7531.

Rename the cases of MIRROR_MASK to MIRROR_PORT_MASK.

Move mt753x_mirror_port_get() and mt753x_port_mirror_set() to mt7530.h as
macros.
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Signed-off-by: David S. Miller <davem@davemloft.net>