disp: msm: sde: take min ib votes from perf config

Changes are made to get minimum ib vote for each bus from
device tree entries rather than static values.

Change-Id: Ibecb44ac6b8673c5d5b8979014c215ab3ce9e43f
Signed-off-by: Andhavarapu Karthik <quic_kartkart@quicinc.com>