soc: swr-mstr: Add delay of 100us after last write during bulk write

There is no delay after last write during bulk write. Add 100us delay
so as to ensure that last write goes fine.

Change-Id: Ifc1585f30eec639ffd6b80dde2e0365f368349d7
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>