Provide optimized ?SUM kernels for NeoverseN1 and related #3130

Job	Run time
TEST (C910V, riscv64-unknown-linux-gnu, riscv64-linux-gnu, NO_SHARED=1 TARGET=C910V)	10m 38s
TEST (RISCV64_GENERIC, riscv64-linux-gnu, riscv64-linux-gnu, NO_SHARED=1 TARGET=RISCV64_GENERIC)	8m 15s
	18m 53s

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