src/meta-openembedded:mbedtls: upgrade 2.16.2 -> 2.16.3

* Mbed TLS 2.16.3 is a maintenance release of the Mbed TLS 2.16 branch, and
  provides bug fixes and minor enhancements.

https://github.com/ARMmbed/mbedtls/releases/tag/mbedtls-2.16.3

Most importantly, this fixes breakage on ARMv5TE platforms:

* Fix the build on ARMv5TE in ARM mode to not use assembly instructions that
  are only available in Thumb mode.

Mbed-TLS/mbedtls#2169

Signed-off-by: Denys Dmytriyenko <denys@ti.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>