android: binder: remove binder.h

binder.h isn't needed to just include a uapi file and set a single
define, so move it into binder.c to save a few lines of code.

Change-Id: Idcd0aba576295bbe0ddf5d18c4b1d1e8efdc8c84
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>