common: fix ansible location

When deploying on arm64, common reports error:
stat /usr/bin/ansible: no such file or directory

The reason is ansible is installed to /usr/local/bin/ansible
rather that /usr/bin/ansible
Fix the issue to call ansible directly, to consider both cases.

Change-Id: Ie90bd9c4d7d3a4b7b0aef884351cb58ed13ebd11
Signed-off-by: Kevin Zhao <kevin.zhao@linaro.org>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>