crypto/arm64: nhpoly1305 - Switch to 'ksimd' scoped guard API

Switch to the more abstract 'scoped_ksimd()' API, which will be modified
in a future patch to transparently allocate a kernel mode FP/SIMD state
buffer on the stack, so that kernel mode FP/SIMD code remains
preemptible in principe, but without the memory overhead that adds 528
bytes to the size of struct task_struct.

Reviewed-by: Eric Biggers <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
Acked-by: Catalin Marinas <[e-mail]>
Signed-off-by: Ard Biesheuvel <[e-mail]>

arch/arm64/crypto/nhpoly1305-neon-glue.c

···
 	do {
 		unsigned int n = min_t(unsigned int, srclen, SZ_4K);
 
-		kernel_neon_begin();
-		crypto_nhpoly1305_update_helper(desc, src, n, nh_neon);
-		kernel_neon_end();
+		scoped_ksimd()
+			crypto_nhpoly1305_update_helper(desc, src, n, nh_neon);
 		src += n;
 		srclen -= n;
 	} while (srclen);