kernel: support for RTL8367C/S switch

kernel: support for RTL8367C/S switch

From driver point of view no differance between rtl8367b and rtl8367s
if it connected through EXT2 (rgmii only).
So this trivial patch add some identification and initialization only.
SGMII/HSGMII mode for EXT1 is not implemented for the sake of patch
clairity.

Signed-off-by: Serge Vasilugin <vasilugin@yandex.ru>
[Fix code format]
Signed-off-by: DENG Qingfang <dengqf6@mail2.sysu.edu.cn>
[add flags to separate chip_num/chip_id detection; drop error print in
rtl8367b_init_regs, drop unnecessary info prints, code style fixes]
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
[rebase; use MII macros]
Signed-off-by: Gaspare Bruno <gaspare@anlix.io>
[code optimization]
Signed-off-by: Mieczyslaw Nalewaj <namiltd@yahoo.com>