net/phy/cortina: Add No firmware upload option

net/phy/cortina: Add No firmware upload option

Current Cortina phy driver assumes that firmware upload
is required during initialization and is dependent
on presence of corresponding macros like CONFIG_CORTINA_FW_ADDR
for compilation.

But Cortina phy has provision to store phy firmware in
attached dedicated EEPROM. And boards designed with such
EEPROM does not require firmware upload.

Add CORTINA_NO_FW_UPLOAD option in cortina.c to support
such boards.

Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>