ARM: dts: msm: Enable BAM mode for spi dtsi node

Enabling the BAM mode for spi driver in sdm429 target. It was
earlier disabled due to time outs observed when spi transfers
are in BAM mode. This is due to build issues and on the latest
builds issue is not seen anymore.

This reverts commit b6a650c9.

Change-Id: I1ae83f28f24e56b93dac8dcaabe8055b1e05db8a
Signed-off-by: Prudhvi Yarlagadda <pyarlaga@codeaurora.org>