Rename mii_stat1000_to_linkmode_lpa_t to
mii_stat1000_mod_linkmode_lpa_t to indicate it modifies the passed
linkmode bitmap, without clearing any other bits.

Add a helper to set/clear bits in a linkmode.

Use this helper to ensure bit are clear which the stat1000 indicates
should not be set.

Fixes: c0ec3c273677 ("net: phy: Convert u32 phydev->lp_advertising to linkmode")
Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

This is one step in allowing phylib to make use of link_mode bitmaps,
instead of u32 for supported and advertised features. Convert the phy
drivers to use bitmaps to indicates the features they support.

Build bitmap equivalents of the u32 values at runtime, and have the
drivers point to the appropriate bitmap. These bitmaps are shared, and
we don't want a driver to modify them. So mark them __ro_after_init.

Within phylib, the features bitmap is currently turned back into a
u32. This will be removed once the whole of phylib, and the drivers
are converted to use bitmaps.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

phylink has some useful helpers to working with linkmode bitmaps.
Move them to there own header so other code can use them.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>