flash-all.sh: support for case that not run lunch

In the cases that we build in a script or built several days before,
we don't want to run "lunch hikey-userdebug" before run flash-all.sh

ANDROID_BUILD_TOP will be only availbe after run lunch command

Change-Id: I06c9479cd05a5178b6d1444eedbc67d743db28ae
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
1 file changed