Indicates the 802.1p priority of a VLAN.
Range: 0-7, 255
The larger the value, the higher the priority.
If the query operation is performed before hwVlanPriority is configured,
the query result is 255, which is invalid.
The meaning of each value is as follows:
best-effort: Best-effort priority(0)
background: Background priority(1)
spare: Spare priority(2)
excellent-effort: Excellent-effort priority(3)
controlled-load: Controlled-load priority(4)
video: Video priority(5)
voice: Voice priority(6)
network-management: Network-management priority(7)