build-all: Don't mix tabs / spaces

Guido says no to tabs in python (however much I may disagree
with him). Regardless of tabs or spaces, you definitely cannot
mix them; future versions of the python interpereter plan to
simply reject files that mix them outright, so we should follow
good style guidelines

Change-Id: I32a30ac3ef430916c534738a7349482d3f151fd5
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
(cherry picked from commit cbebac12150f62ec6f9810f09366d5cf66d60875)