msm: mdss: debugfs: xlog: enable xlog debug by default

This change will enable by default the display
driver debugging features in non performance
builds to: dump MDSS registers during failures,
panic during fatal display driver errors and
enable some logging into an internal buffer
(to avoid logging overhead).

Change-Id: Idc5e2dbd6960ee568f3e18a103c248b20faca548
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>