ARM: dts: msm: Update bus bandwidth votes for sdhci on 8974

Some versions of 8974 supports eMMC HS400 mode providing maximum
throughput of 400MB/s. Update the list of bus bandwidth votes to
make sure appropriate vote is placed in this mode.

Change-Id: I5e3bed70d8c8c1c6423483f7469849823e3ebb2c
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>