msm_fb: display: Keep fb1 for MDP version < 4.0.2

For better memory usage, fb1 memory allocation is removed for
targets like 8960 which support BF pipe and true mirroring but
required for targets like 7x30 and 8660 which still needs fb1
for border fill.

CRs-fixed: 364669
Change-Id: Id741223a0107e356b9164b582aa1f901caa21988
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>