net: stmmac: add flexible PPS to dwmac 4.10a

All the registers and the functionalities used in the callback
dwmac5_flex_pps_config() are common between dwmac 4.10a [1] and
5.00a [2].

Reuse the same callback for dwmac 4.10a too.

Tested on STM32MP15x, based on dwmac 4.10a.

[1] DWC Ethernet QoS Databook 4.10a October 2014
[2] DWC Ethernet QoS Databook 5.00a September 2017

Signed-off-by: Antonio Borneo <antonio.borneo@st.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>