Kbuild arm: set Wno-vectorizer-no-neon flag

Set Wno-vectorizer-no-neon flag to disable warning
"Vectorization flags ignored because armv7/armv8
and neon not set [-Wvectorizer-no-neon]".

Change-Id: Ib130302db66686b0bd91102436a93c24233aa755
Signed-off-by: Naitik Bharadiya <bharad@codeaurora.org>