net: phy: meson-gxl: add g12a support

[ Upstream commit 5c3407abb3382fb0621a503662d00495f7ab65c4 ]

The g12a SoC family uses the type of internal PHY that was used on the
gxl family. The quirks of gxl family, like the LPA register corruption,
appear to have been resolved on this new SoC generation.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 69ff53e4a4c9 ("net: phy: meson-gxl: use MMD access dummy stubs for GXL, internal PHY")
Signed-off-by: Sasha Levin <sashal@kernel.org>