Don't include mbedtls/platform.h unconditionally

Programs must not include mbedtls/platform.h if MBEDTLS_PLATFORM_C is
not defined. Test suites don't need to include mbedtls/platform.h
because helpers.function takes care of it.

This commit also removes a stray `;` which is technically not standard C.
diff --git a/tests/suites/test_suite_psa_crypto_init.function b/tests/suites/test_suite_psa_crypto_init.function
index 3596504..132fe82 100644
--- a/tests/suites/test_suite_psa_crypto_init.function
+++ b/tests/suites/test_suite_psa_crypto_init.function
@@ -11,7 +11,6 @@
 
 #include "mbedtls/entropy.h"
 #include "mbedtls/entropy_poll.h"
-#include "mbedtls/platform.h"
 
 #define MIN( x, y ) ( ( x ) < ( y ) ? ( x ) : ( y ) )
 #define MAX( x, y ) ( ( x ) > ( y ) ? ( x ) : ( y ) )
@@ -41,7 +40,7 @@
         output[i] = i;
     ++state->step;
     return( 0 );
-};
+}
 
 #define ENTROPY_SOURCE_PLATFORM                 0x00000001
 #define ENTROPY_SOURCE_TIMING                   0x00000002