net: sh_eth: modify for both modules

This current driver supports ETHER and GETHER. But we cannot use them at same time because the defination of registers is hardcoded by #ifdef in sh_eth.h.
The patches modify the defination to arrays of const. Then we can choose the array by platform_device's data. The patches also modify for GETHER. The current driver used the "#ifdef CONFIG_CPU_SUBTYPE_SH7763". The patches remove it and check by other method for GETHER.