IFU & ICache clock gating

[ngc7331]

Port from nanhu-clockgated

[XiangShanRobot]

[Generated by IPC robot]
commit: b42b57f

commit	astar	copy_and_run	coremark	gcc	gromacs	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
b42b57f	1.878	0.461	2.100	1.213	2.895	2.182	1.398	0.920	1.421	1.123	3.617	2.666	2.302	3.165

master branch:

commit	astar	copy_and_run	coremark	gcc	gromacs	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
a42a7ff	1.878	0.461	2.100	1.213	2.914	2.181	1.395	0.920	1.421	1.126	3.617	2.659	2.302	3.165
b15e4c0	1.878	0.461	2.100	1.213	2.895	2.181	1.395	0.919	1.421	1.128	3.617	2.659	2.302	3.165
3c5d56a	1.878	0.461	2.100	1.209	2.913	2.182	1.395	0.920	1.421	1.123	3.617	2.660	2.302	3.165
8abe181	1.878	0.461	2.100	1.213	2.895	2.179	1.395	0.919	1.421	1.125	3.617	2.666	2.302	3.165
13156de	1.878	0.461	2.100	1.213	2.895	2.182	1.397	0.919	1.421	1.126	3.617	2.660	2.302	3.165
1fcb3bc	1.878	0.461	2.100	1.211	2.895	2.181	1.395	0.920	1.421	1.123	3.617	2.659	2.302	3.165
f3c16e1	1.878	0.461	2.100	1.213	2.895	2.182	1.396	0.920	1.421	1.126	3.617	2.659	2.302	3.165
45f43e6	1.878	0.461	2.100	1.211	2.895	2.182	1.395	0.920	1.421	1.127	3.617	2.659	2.302	3.165
8fae59b	1.878	0.461	2.100	1.213	2.913	2.182	1.394	0.920	1.421	1.123	3.617	2.647	2.302	3.165
a61a35e	1.879	0.460	2.092	1.200	2.895	2.176	1.394	0.917	1.436	1.125	3.617	2.663	2.298	3.134

[ngc7331]

#2957