Allow SFP quirks to override the Autoneg, Pause and Asym_Pause bits in
the support mask.

Some modules have an inaccessible PHY on which is only accessible via
2500base-X without Autonegotiation. We therefore want to be able to
clear the Autoneg bit. Rearrange sfp_parse_support() to allow a SFP
modes quirk to override this bit.
Tested-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>