Camera3: Flush device before ZSL reprocess

Call flush before sending ZSL reprocess request. This not only ensures no
in-flight requests pending in the HAL before ZSL reprocess request, but also
makes reprocess request to be processed by the HAL sooner.

Bug: 12230973
Change-Id: I4c9e5a0fb75ccdc1e8861262c08d599d04170b7f
2 files changed