Revert "common, env: Fix support for environment in i2c eeprom"

Since i2c_init_all always sets the bus back to CONFIG_SYS_SPD_BUS_NUM
for compatibility reasons, it means that any eeprom not located on this
CONFIG_SYS_SPD_BUS_NUM is not accessible with the eeprom commands, even
if you change the bus number with an i2c dev command before.

Furthermore i2c_init_all should disappear and is currently only called
from the early board initialisation sequences, it is not suited for
other usage.

This reverts commit 01a0c647.

Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
Acked-by: Matthias Fuchs <matthias.fuchs@esd.eu>