Move CONFIG_AIO to android-base.

CONFIG_AIO has legitimate use for the functionfs
driver, which is used with adb and mtp. It is now
required to be enabled for better performance
with those services.

Bug: 37916658
Test: None
Change-Id: Ic9adb3340f6b3230798653e0bb08bbafdd550efd
Signed-off-by: Jerry Zhang <zhangjerry@google.com>