msm: camera: isp: Fix issues in releasing ISP resources

This change fixes several issues while releasing ISP resources. Without
this change, multiple sequence of acquire/release of VFE Bus resources
and ISP Context will fail.

Change-Id: Ibb5ce58db6640d2b7e1d39f6bd5e4a1cd0aa3bb9
Signed-off-by: Jing Zhou <jzhou70@codeaurora.org>
Signed-off-by: Harsh Shah <harshs@codeaurora.org>