net: stmmac: move version handling into own function

net: stmmac: move version handling into own function

Move the version handling out of stmmac_hwif_init() and into its own
function, returning the version information through a structure.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1vDteg-0000000CCBr-2m7q@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>