First try to purge out ClockGroup API #881

Job	Run time
riscv-tests (DefaultConfig)	11m 56s
riscv-tests (DefaultBufferlessConfig)	12m 4s
emulator (DefaultSmallConfig)	12m 4s
riscv-tests (DefaultRV32Config)	12m 10s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.DefaultC...	11m 50s
emulator (DualBankConfig)	11m 59s
riscv-arch-test	0s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.DefaultR...	11m 57s
riscv-tests (TinyConfig)	12m 10s
emulator (DualChannelConfig)	12m 3s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.WithDebu...	11m 58s
riscv-tests (DefaultFP16Config)	11m 53s
emulator (DualChannelDualBankConfig)	11m 59s
jtag-dtm-test (freechips.rocketchip.system.WithJtagDTMSystem_freechips.rocketchip.system.WithDebu...	11m 59s
emulator (RoccExampleConfig)	12m 7s
emulator (Edge128BitConfig)	11m 57s
emulator (Edge32BitConfig)	12m 11s
emulator (QuadChannelBenchmarkConfig)	12m 12s
emulator (EightChannelConfig)	11m 57s
emulator (DualCoreConfig)	12m 1s
emulator (MemPortOnlyConfig)	12m 13s
emulator (MMIOPortOnlyConfig)	12m 4s
emulator (CloneTileConfig)	12m 13s
emulator (HypervisorConfig)	11m 59s
	4h 36m 56s

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