net: dsa: microchip: update tag_ksz masks for KSZ9477 family

Remove magic number 7 by introducing a GENMASK macro instead.
Remove magic number 0x80 by using the BIT macro instead.

Signed-off-by: Pieter Van Trappen <pieter.van.trappen@cern.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20240909134301.75448-1-vtpieter@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>