run-build.sh: Remove superfluous handling in case BUILD_TARGET is set

After recent refactor of splitting build command to seperate sub-commands,
we don't need to do adhoc parsing with "head" like before. So, remove to
avoid confusion.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ib4c66c384d5aaa6f30edec50776f031ab87cd65c
1 file changed