ARM: multi_v7_defconfig: enable Lima driver

A bunch of armv7 boards can now use the Lima driver, let's enable it
in defconfig, it will be useful to have it enabled for KernelCI
boot and runtime testing.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Olof Johansson <olof@lixom.net>