msm: mdss: add vbif debug bus support in xlog

VBIF debug bus test points provides the ARB/XIN
client status. These test points information is
required when MDSS core has requested some transaction
but they are not returning back. This change adds
the support for common code dump/log the test points
and adds the offset for msm8996 configuration.

Change-Id: I376a9e50aaaedb170bf4904551450206a85e4a1c
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>