msm: mdss: restructure tearcheck config

Since we have a separate function for tear check enable.
Tearcheck config with enable flag is not required, and
redundant. Remove enable flag and improper usage of
the function.

Change-Id: I0835f858cc63a41e01a669069677322da408f245
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>