hwc2: Change Get and Destroy Layer Error to Warning

Since layer creation and destruction are in the hands of applications,
SDM needs not flag an error if an invalid operation is requested on a
layer. Appropriate error code should be returned and client is
responsible to handle.

Change-Id: Idccc882443400c312068ce85261f7f0032d9c2b7
CRs-Fixed: 2306744
1 file changed