net: dwc_eth_qos: Split STM32 glue into separate file

Move STM32 glue code into separate file to contain the STM32 specific
code outside of the DWMAC core code. No functional change.

Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Christophe ROULLIER<christophe.roullier@foss.st.com>
4 files changed