net: dsa: mv88e6xxx: enable support for 88E6361 switch

Marvell 88E6361 is an 8-port switch derived from the
88E6393X/88E9193X/88E6191X switches family. It can benefit from the
existing mv88e6xxx driver by simply adding the proper switch description in
the driver. Main differences with other switches from this
family are:
- 8 ports exposed (instead of 11): ports 1, 2 and 8 not available
- No 5GBase-x nor SFI/USXGMII support

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>