net: phy: motorcomm: Add pad drive strength cfg support

net: phy: motorcomm: Add pad drive strength cfg support

The motorcomm phy (YT8531) supports the ability to adjust the drive
strength of the rx_clk/rx_data, and the default strength may not be
suitable for all boards. So add configurable options to better match
the boards.(e.g. StarFive VisionFive 2)

Original commit: https://github.com/SaminGuo/linux/commit/3732faf2239b77478022246b9ac62902ec30c2c6

Change-Id: Ic805273b769f3ee47eab4aec1c16c6633d466ac8
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>