msm: ipa: fix header table reset bug

Header table reset was also resetting the "default" header
leading to failures in Header Insertion unit tests. This
commit fixes that bug.

Change-Id: I8c412febb27f6077e250936015b3f5c68f3ce61e
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>