net: phy: meson-gxl: check phy_write return value

[ Upstream commit 9042b46eda33ef5db3cdfc9e12b3c8cabb196141 ]

Always check phy_write return values. Better to be safe than sorry

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>