net: phy: phy_caps: Introduce phy_caps_valid

With the link_capabilities array, it's trivial to validate a given mask
againts a <speed, duplex> tuple. Create a helper for that purpose, and
use it to replace a phy_settings lookup in phy_check_valid();

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20250307173611.129125-6-maxime.chevallier@bootlin.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>