clean up duplicate assignment of cpus newer than POWER10 #6040

Job	Run time
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 44s
build (ubuntu-latest, gfortran, make)	23m 58s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	2m 56s
build (macos-latest, gfortran, cmake)	30m 16s
build (ubuntu-latest, flang, make)	4m 54s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	11m 41s
msys2 (CLANG64, int32, Release)	15m 30s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	4m 12s
msys2 (UCRT64, int32, Release)	14m 8s
msys2 (CLANG64, int64, Release)	15m 48s
build (macos-latest, gfortran, make)	6m 10s
build (ubuntu-latest, gfortran, cmake)	47m 32s
msys2 (MINGW32, int32, Release)	15m 4s
neoverse_build	7m 50s
build (ubuntu-latest, flang, cmake)	10m 12s
msys2 (UCRT64, int64, Release)	13m 25s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	2m 50s
	3h 50m 10s

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