Remove mutexes from ECP hardware acceleration

Protecting the ECP hardware acceleratior with mutexes is inconsistent with the
philosophy of the library. Pre-existing hardware accelerator interfaces
leave concurrency support to the underlying platform.

Fixes #863
diff --git a/ChangeLog b/ChangeLog
index e654c1f..741d1f4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,6 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
-= mbed TLS x.x.x branch released xxxx-xx-xx
+= mbed TLS 2.x.x released xxxx-xx-xx
 
 Features
    * Add the functions mbedtls_platform_setup() and mbedtls_platform_teardown()
@@ -16,10 +16,6 @@
      qualifier from the functions mbedtls_aes_decrypt, mbedtls_aes_encrypt,
      mbedtls_ssl_ciphersuite_uses_ec and mbedtls_ssl_ciphersuite_uses_psk.
 
-Changes
-   * Added config.h option MBEDTLS_NO_UDBL_DIVISION, to prevent the use of
-     64-bit division.
-
 Bugfix
    * Add a check if iv_len is zero, and return an error if it is zero. reported
      by roberto. #716
@@ -51,6 +47,8 @@
      a fatal error in the vrfy callback.
 
 Changes
+   * Added config.h option MBEDTLS_NO_UDBL_DIVISION, to prevent the use of
+     64-bit division.
    * Removed mutexes from ECP hardware accelerator code. Now all hardware
      accelerator code in the library leaves concurrency handling to the
      platform. Reported by Steven Cooreman. #863