ANDROID: microdroid: disable CONFIG_MODULES

There is no need for microdroid kernel to support loading modules. If
a microdroid VM wants to use vendor kernel modules for device
assignment, it should use GKI as guest kernel.

Bug: 325331778
Test: run microdroid tests
Change-Id: I074e65ee5df51103d942a744de290c66583ec2cc
Signed-off-by: Nikita Ioffe <ioffe@google.com>