cmd: eeprom: Fix config dependency

We should have CONFIG_DM_I2C or CONFIG_SYS_I2C_LEGACY enabled in
order for `cmd/eeprom.c` to compile as it depends on the i2c functions
which are not compiled otherwise. Update the Kconfig entry for the
'eeprom' command correspondingly.

Signed-off-by: Ivan Orlov <ivan.orlov@codethink.co.uk>
Reviewed-by: Tom Rini <trini@konsulko.com>