Fix compilation of the NeoverseN2 SBGEMM kernel #5977

Job	Run time
build (ubuntu-latest, gfortran, make)	22m 12s
neoverse_build	8m 5s
build (macos-latest, gfortran, make)	6m 1s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	3m 28s
build (ubuntu-latest, flang, make)	5m 8s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 56s
msys2 (CLANG64, int32, Release)	1h 9m 11s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	2m 59s
msys2 (UCRT64, int32, Release)	1h 39m 31s
build (ubuntu-latest, gfortran, cmake)	46m 31s
build (ubuntu-latest, flang, cmake)	43m 47s
msys2 (UCRT64, int64, Release)	1h 36m 54s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	2m 42s
build (macos-latest, gfortran, cmake)	25m 57s
msys2 (CLANG64, int64, Release)	1h 12m 27s
msys2 (MINGW32, int32, Release)	1h 4m 5s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	1h 25m 44s
	10h 58m 38s

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