net/mlx5: fix pre-2.40 binutils assembler error

Old binutils versions require a slightly stricter syntax for the .arch_extension
directive and fail with the extra semicolon:

/tmp/cclfMnj9.s:656: Error: unknown architectural extension `simd;'

Drop the semicolon to make it work with all supported toolchain version.

Link: https://lore.kernel.org/all/20251001163655.GA370262@ax162/
Reported-by: Paolo Abeni <pabeni@redhat.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Fixes: fd8c821 ("net/mlx5: Improve write-combining test reliability for ARM64 Grace CPUs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Patrisious Haddad <phaddad@nvidia.com>
Link: https://patch.msgid.link/20251006115640.497169-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: arndb

drivers/net/ethernet/mellanox/mlx5/core/wc.c

@@ -266,7 +266,7 @@ static void mlx5_iowrite64_copy(struct mlx5_wc_sq *sq, __be32 mmio_wqe[16],
 	if (cpu_has_neon()) {
 		kernel_neon_begin();
 		asm volatile
-		(".arch_extension simd;\n\t"
+		(".arch_extension simd\n\t"
 		"ld1 {v0.16b, v1.16b, v2.16b, v3.16b}, [%0]\n\t"
 		"st1 {v0.16b, v1.16b, v2.16b, v3.16b}, [%1]"
 		: