stmmac: extend CSR Clock Range programming

The CSR Clock Range has been reworked and new macros has
been added in the platform header to allow the CSR Clock
Range selection in the GMII Address Register.
The previous work didn't add the other fields
that can be used to achieve MDC clock of frequency
higher than the IEEE 802.3 specified frequency limit
of 2.5 MHz and program a clock divider of lower value.
On such platforms, these are used indeed so this patch
adds them.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>