net: sparx5: Fix add vlan when invalid operation

net: sparx5: Fix add vlan when invalid operation

BugLink: https://bugs.launchpad.net/bugs/1964361
[ Upstream commit b3a34dc362c03215031b268fcc0b988e69490231 ]

Check if operation is valid before changing any
settings in hardware. Otherwise it results in
changes being made despite it not being a valid
operation.

Fixes: 78eab33bb68b ("net: sparx5: add vlan support")
Signed-off-by: Casper Andersson <casper.casan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>