net: phy: Remove unused including <linux/version.h>

Eliminate the follow versioncheck warning:

./drivers/net/phy/mxl-gpy.c: 9 linux/version.h not needed.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: chongjiapeng <jiapeng.chong@linux.alibaba.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>