Fix accidental mis-named field

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 39579d5..1e89aff 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -307,7 +307,7 @@
     uint8_t MBEDTLS_PRIVATE(flags) : 2;
 
     /** The block size, in bytes. */
-    uint8_t MBEDTLS_PRIVATE(block_size2) : 2;
+    uint8_t MBEDTLS_PRIVATE(block_size) : 2;
 
 } mbedtls_cipher_info_t;
 
@@ -548,7 +548,7 @@
         return 0;
     }
 
-    int packed = info->MBEDTLS_PRIVATE(block_size2);
+    int packed = info->MBEDTLS_PRIVATE(block_size);
     return (size_t) (MBEDTLS_CIPHER_BLOCK_SIZE_UNPACK(packed));
 }
 
@@ -690,7 +690,7 @@
         return 0;
     }
 
-    int packed = ctx->MBEDTLS_PRIVATE(cipher_info)->MBEDTLS_PRIVATE(block_size2);
+    int packed = ctx->MBEDTLS_PRIVATE(cipher_info)->MBEDTLS_PRIVATE(block_size);
     return (unsigned int) MBEDTLS_CIPHER_BLOCK_SIZE_UNPACK(packed);
 }