lib/crypto: arm64/poly1305: Remove obsolete chunking logic

Since commit aefbab8 ("arm64: fpsimd: Preserve/restore kernel mode
NEON at context switch"), kernel-mode NEON sections have been
preemptible on arm64.  And since commit 7dadeaa ("sched: Further
restrict the preemption modes"), voluntary preemption is no longer
supported on arm64 either.  Therefore, there's no longer any need to
limit the length of kernel-mode NEON sections on arm64.

Simplify the Poly1305 code accordingly.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260401000548.133151-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

lib/crypto/arm64/poly1305.h

@@ -27,17 +27,11 @@ static void poly1305_blocks(struct poly1305_block_state *state, const u8 *src,
 			    unsigned int len, u32 padbit)
 {
 	if (static_branch_likely(&have_neon) && likely(may_use_simd())) {
-		do {
-			unsigned int todo = min_t(unsigned int, len, SZ_4K);
-
-			scoped_ksimd()
-				poly1305_blocks_neon(state, src, todo, padbit);
-
-			len -= todo;
-			src += todo;
-		} while (len);
-	} else
+		scoped_ksimd()
+			poly1305_blocks_neon(state, src, len, padbit);
+	} else {
 		poly1305_blocks_arm64(state, src, len, padbit);
+	}
 }
 
 #define poly1305_mod_init_arch poly1305_mod_init_arch