POWERPC: Bring the fs_no calculation to the relevant SoC enumeration

The fs_no mean used to be fs_enet driver driven, hence it was an
enumeration across all the possible fs_enet "users" in the SoC. Now, with
QE on the pipeline, and to make DTS descriptions more clear, fs_no features
relevant SoC part number, with additional field to describe the SoC type.

Another reason for that is now not only fs_enet is going to utilize those
stuff. There might be UART, HLDC, and even USB, so to prevent confusion and
be ready for upcoming OF_device transfer, fs_enet and cpm_uart drivers were
updated in that concern, as well as the relevant DTS.

Signed-off-by: Vitaly Bordug <vbordug@ru.mvista.com>