Minor improvements

Correct style and free entropy context prior to freeing the ctr drbg context,
as the latter keeps a reference to the entropy context. While it doesn't cause
any problems the way it was before because the ctr drbg context is not used any
longer after freeing the entropy, it's nonetheless cleaner this way.

programs/pkey/pk_decrypt.c

@@ -119,8 +119,8 @@ int main( int argc, char *argv[] )
         goto exit;
     }
 
-    for( i=0; fscanf( f, "%02X", &c ) > 0 &&
-              i < (int) sizeof( buf ); i++ )
+    for( i = 0; fscanf( f, "%02X", &c ) > 0 &&
+             i < (int) sizeof( buf ); i++ )
     {
         buf[i] = (unsigned char) c;
     }
@@ -148,9 +148,10 @@ int main( int argc, char *argv[] )
     ret = 0;
 
 exit:
+
     mbedtls_pk_free( &pk );
-    mbedtls_ctr_drbg_free( &ctr_drbg );
     mbedtls_entropy_free( &entropy );
+    mbedtls_ctr_drbg_free( &ctr_drbg );
 
 #if defined(MBEDTLS_ERROR_C)
     if( ret != 0 )

programs/pkey/pk_encrypt.c

@@ -152,9 +152,10 @@ int main( int argc, char *argv[] )
     mbedtls_printf( "\n  . Done (created \"%s\")\n\n", "result-enc.txt" );
 
 exit:
+
     mbedtls_pk_free( &pk );
-    mbedtls_ctr_drbg_free( &ctr_drbg );
     mbedtls_entropy_free( &entropy );
+    mbedtls_ctr_drbg_free( &ctr_drbg );
 
 #if defined(MBEDTLS_ERROR_C)
     if( ret != 0 )