types: mode to include/zephyr

With the new <zephyr/> include prefix, the "types" header ended up being
located in <zephyr/zephyr/types.h>, ie weird. Code that hasn't migrated
to <zephyr/zephyr/types.h> (no occurences in tree) will be automatically
prepared for the removal of the legacy include path. Most applications
will not be impacted as both include and include/zephyr are now in the
include path, and they'll be already prepared for the future.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>