msm: mdss: perform hardware rev init earlier during probe

Perform revision initialization as soon as possible in order to have
all capabilities that depend on revision read from hardware
enumerated by the time we start parsing and doing other
initialization.

CRs-Fixed: 987777
Change-Id: Ide1fa99b876a3347a4e46c11261a9e7a32b8f47a
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>