clean up duplicate assignment of cpus newer than POWER10 #1489

Job	Run time
TEST (LOONGSON3R5, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSON3R5)	8m 5s
TEST (DYNAMIC_ARCH, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=GENERIC)	15m 35s
TEST (LA264, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA264)	7m 44s
TEST (LA64_GENERIC, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA64_GENERIC)	8m 23s
TEST (LOONGSON2K1000, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSON2K1000)	10m 15s
TEST (LOONGSONGENERIC, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSONGENERIC)	7m 56s
TEST (LA464, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA464)	9m 0s
	1h 6m 58s

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