ARM: multi_v7_defconfig: Enable generic SoC internal OMAP regulators

ABB and PBIAS are internal LDO control regulators that are needed for
maintaining proper functionality of OMAP architecture SoCs. Enable the
same. PBIAS is already enabled, so just enable ABB regulator as well.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Olof Johansson <olof@lixom.net>