ethtool: plca: fix plca enable data type while parsing the value

ethtool: plca: fix plca enable data type while parsing the value

The ETHTOOL_A_PLCA_ENABLED data type is u8. But while parsing the
value from the attribute, nla_get_u32() is used in the plca_update_sint()
function instead of nla_get_u8(). So plca_cfg.enabled variable is updated
with some garbage value instead of 0 or 1 and always enables plca even
though plca is disabled through ethtool application. This bug has been
fixed by parsing the values based on the attributes type in the policy.

Fixes: 8580e16c28f3 ("net/ethtool: add netlink interface for the PLCA RS")
Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230908044548.5878-1-Parthiban.Veerasooran@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>