net: phy: aquantia: delete aqr_firmware_read_fingerprint() prototype

net: phy: aquantia: delete aqr_firmware_read_fingerprint() prototype

This is a development artifact of commit a76f26f7a81e ("net: phy:
aquantia: support phy-mode = "10g-qxgmii" on NXP SPF-30841 (AQR412C)").
This function name isn't used. Instead we have aqr_build_fingerprint()
in aquantia_main.c.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250908134313.315406-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>