GPU: Some fixes

[davidrohr]

@fweig : could you have a quick look on the changes in the Clusterizer?
In principle they should not change anything at all for normal processing, so should be harmless.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 108a1ba at 2026-10-11 14:42:

## sw/BUILD/O2-latest/log
/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/GPU/GPUTracking/TPCClusterFinder/GPUTPCCFDecodeZS.cxx:51:39: error: 'class o2::gpu::GPUTPCClusterFinder' has no member named 'IsDeviceProcessor'; did you mean 'InitializeProcessor'?
/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/GPU/GPUTracking/TPCClusterFinder/GPUTPCCFDecodeZS.cxx:376:39: error: 'o2::gpu::GPUTPCCFDecodeZSLinkBase::processorType' {aka 'class o2::gpu::GPUTPCClusterFinder'} has no member named 'IsDeviceProcessor'; did you mean 'InitializeProcessor'?
ninja: build stopped: subcommand failed.

Full log here.