ARM: mvebu: update mvebu_v7_defconfig with features needed for Armada 388 GP

The Armada 388 GP board has the following hardware features that were
not enabled in mvebu_v7_defconfig:

 * An AT24 I2C EEPROM (also used by armada-xp-lenovo-ix4-300d)
 * A PCA9555 I2C GPIO expander
 * Several fixed regulators

Therefore, this commit adds the necessary options to mvebu_v7_defconfig.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>