<kernel> compat check can be split

Split <kernel> check into its own check flag so that we
can check only the compatibility between <kernel> tag
in fwk compat matrix and runtime kernel.

Test: Vts Treble Vintf Test
Test: libvintf_test
Test: vintf_object_test

Bug: 64301876
Change-Id: Ia5891ef46be1dd6e69123ab6cbeeb5d5d4868c56
2 files changed