fix grammar issue in comment

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/aesce.c b/library/aesce.c
index 5833a5d..653e28b 100644
--- a/library/aesce.c
+++ b/library/aesce.c
@@ -310,7 +310,7 @@
                        vreinterpretq_p64_u8(b)));
 }
 
-/* GHASH do 128b polynomial multiplication on block on GF(2^128) defined by
+/* GHASH does 128b polynomial multiplication on block in GF(2^128) defined by
  * `x^128 + x^7 + x^2 + x + 1`.
  *
  * Arm64 only has 64b->128b polynomial multipliers, we need to do 4 64b