devtool: deploy-target: Remove stripped binaries in pseudo context

deploy-target may fail the second time with "pseudo abort" because
devtool-deploy-target-stripped is deleted outside of pseudo's fakeroot
context.

Signed-off-by: Florian Amstutz <florian.amstutz@scs.ch>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>