ARM: dts: msm: update DDR bw IB votes for sdm439 target

Update DDR bw table IB vote with proper calculation from frequency
for sdm439 target.

Change-Id: I13be739c8d466ec4fd42996cdf7af16c66228c24
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>