Rename the platform specific crypto_platform

To avoid collisions between the psa `crypto_platform.h` file and the
platform specific `crypto_platform.h` file, for the init \ terminate
functions, rename the latter to `crypto_device_platform`.

Author: Ron Eldor

features/cryptocell/FEATURE_CRYPTOCELL310/Readme.md

@@ -24,5 +24,5 @@ To port your CC 310 driver to Mbed OS on your specific target, do the following:
 1. In `features/cryptocell/FEATURE_CRYPTOCELL310/TARGET_<target name>`, add your platform-specific libraries for all toolchains in `TOOLCHAIN_ARM`, `TOOLCHAIN_GCC_ARM` and `TOOLCHAIN_IAR` respectively.
 1. Add your CC setup code:
 	* Implement `crypto_platform_setup()` and `crypto_platform_terminate()` to enable CC on your platform, in case you have board-specific setup functionality, required for CC setup. You MUST call 'SaSi_LibInit()` and 'SaSi_LibFini()' respectively in these functions.
-	* Define `crypto_platform_ctx` in `crypto_platform.h` in a way that suits your implementation.
+	* Define `crypto_platform_ctx` in `crypto_device_platform.h` in a way that suits your implementation.
 

features/cryptocell/FEATURE_CRYPTOCELL310/TARGET_MCU_NRF52840/crypto_platform.c renamed to features/cryptocell/FEATURE_CRYPTOCELL310/TARGET_MCU_NRF52840/crypto_device_platform.c

@@ -22,7 +22,7 @@
 #define __PLATFORM_ALT__
 #include "platform_mbed.h"
 #if defined(MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT)
-#include "crypto_platform.h"
+#include "crypto_device_platform.h"
 /**
  * \brief   The platform context structure.
  *