hikey: factory-images: Remove ANDROID_TOP_DIR assignment

The script here incorrectly sets the ANDROID_TOP_DIR assignment,
which breaks the use case documented in README.

For building with a pre-built image, one should have the ANDROID_TOP_DIR set
by build/setenv.sh

Change-Id: If1caa3edad3ab597534a379e8952c7c6621dd2d8
Signed-off-by: John Stultz <john.stultz@linaro.org>
1 file changed