arm64/dts: camera: Troika : set rear default multi_ch to 2 and modify fimc_is_sensor2...

arm64/dts: camera: Troika	: set rear default multi_ch to 2 and modify fimc_is_sensor2 to use dma3 ch

- related to cts test: android.hardware.camera2.cts.MultiViewTest#testDualCameraPreview

CRs-fixed: (CR)

Change-Id: Iea578f52632ffebc284bbbda503c2ed58f7a44dc
Signed-off-by: xff <fangfang.xu@samsung.com>
Reviewed-on: https://gerrit.mot.com/1329503
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Dawei Wang <wangdw10@motorola.com>
Reviewed-by: Zhichao Chen <chenzc2@motorola.com>
Submit-Approved: Jira Key