Export common since it's being used directly.

android_color_mode was replaced with ColorMode and
so libui uses the graphics common hal HIDL code
directly and so should also export it.

(used and exported by GraphicsTypes.h)

Bug: 73824924
Test: modules using this header have build breakage fixed
    and have the header properly delivered to them without
    having to add it to their makefiles.

Change-Id: I6318719b2b5f9cc294273e45dd5015d7258c50f9