r8169: use dev_err_probe in rtl_get_ether_clk

Tiny improvement, let dev_err_probe() deal with EPROBE_DEFER.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/b0c4ebcf-2047-e933-b890-8a20e4bdb19f@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>