mediapc: Limit 4k secure instances to 2

Also, account for maxInstances supported by the codec in 4k + 1080p
usecase.

Bug: 290294604
Bug: 296165449
Test: atest CtsMediaPerformanceClassTestCases:MultiDecoderPerfTest \
CtsMediaPerformanceClassTestCases:MultiDecoderPairPerfTest

Change-Id: I62c37a9d410f00968b644b9764d0d13710e6953a
1 file changed