timing(icache): restore the relaxation of ICG for icache data

[my-mayfly]

Revert #4246

[my-mayfly]

Based on the feedback from the physical backend, perhaps relaxing the clock gating of the data can achieve better timing results.

[XiangShanRobot]

[Generated by IPC robot]
commit: 5adf4cd

commit	astar	copy_and_run	coremark	gcc	gromacs	hmmer-Vector	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
5adf4cd	1.819	0.442	2.634	1.239	2.144	1.498	2.145	2.359	0.943	1.388	1.998	3.101	2.555	2.272	3.300

master branch:

commit	astar	copy_and_run	coremark	gcc	gromacs	hmmer-Vector	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
4b9ddb8	1.819	0.442	2.634	1.235	2.144	1.498	2.145	2.359	0.943	1.380	1.998	3.101	2.555	2.272	3.300
4aeb0b1	1.819	0.442	2.634	1.232	2.144	1.498	2.145	2.359	0.943	1.380	1.998	3.101	2.555	2.272	3.300
9e12e8e	1.819	0.442	2.634	1.241	2.144	1.498	2.145	2.359	0.943	1.388	1.998	3.101	2.555	2.272	3.300
5f84a7f	1.819	0.442	2.634	1.236	2.144	1.498	2.145	2.359	0.943	1.380	1.998	3.101	2.555	2.272	3.300
c590fb3	1.819	0.442	2.634	1.233	2.144	1.498	2.145	2.359	0.943	1.388	1.998	3.101	2.555	2.272	3.300
981114e	1.819	0.442	2.634	1.231	2.144	1.498	2.145	2.359	0.943	1.380	1.998	3.101	2.555	2.272	3.300
f5217f4	1.819	0.442	2.634	1.235	2.144	1.498	2.145	2.359	0.943	1.380	1.998	3.101	2.555	2.272	3.300
977ac3b	1.819	0.442	2.634	1.231	2.144	1.498	2.145	2.359	0.943	1.388	1.998	3.101	2.555	2.272	3.300
75efee3	1.819	0.442	2.634	1.223	2.144	1.498	2.145	2.359	0.943	1.388	1.998	3.101	2.555	2.272	3.300