Zephyr: improve order of random seed sources

When using Zephyr, we also want to use the proper wc_GenerateSeed
method. However, if one of the defines is set (e.g., NO_STM32_RNG), the
Zephyr option is ignored, although it would work. Hence, we have to
change the order in which these settings for the source of a random seed
are evaluated.

Signed-off-by: Tobias Frauenschläger <t.frauenschlaeger@me.com>

Author: Frauschi

wolfcrypt/src/random.c

@@ -3506,20 +3506,6 @@ int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
      * extern int myRngFunc(byte* output, word32 sz);
      */
 
-#elif defined(WOLFSSL_SAFERTOS) || defined(WOLFSSL_LEANPSK) || \
-      defined(WOLFSSL_IAR_ARM)  || defined(WOLFSSL_MDK_ARM) || \
-      defined(WOLFSSL_uITRON4)  || defined(WOLFSSL_uTKERNEL2) || \
-      defined(WOLFSSL_LPC43xx)  || defined(NO_STM32_RNG) || \
-      defined(MBED)             || defined(WOLFSSL_EMBOS) || \
-      defined(WOLFSSL_GENSEED_FORTEST) || defined(WOLFSSL_CHIBIOS) || \
-      defined(WOLFSSL_CONTIKI)  || defined(WOLFSSL_AZSPHERE)
-
-    /* these platforms do not have a default random seed and
-       you'll need to implement your own wc_GenerateSeed or define via
-       CUSTOM_RAND_GENERATE_BLOCK */
-
-    #define USE_TEST_GENSEED
-
 #elif defined(WOLFSSL_ZEPHYR)
 
         #include <version.h>
@@ -3630,6 +3616,20 @@ int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
         return ret;
     }
 
+#elif defined(WOLFSSL_SAFERTOS) || defined(WOLFSSL_LEANPSK) || \
+      defined(WOLFSSL_IAR_ARM)  || defined(WOLFSSL_MDK_ARM) || \
+      defined(WOLFSSL_uITRON4)  || defined(WOLFSSL_uTKERNEL2) || \
+      defined(WOLFSSL_LPC43xx)  || defined(NO_STM32_RNG) || \
+      defined(MBED)             || defined(WOLFSSL_EMBOS) || \
+      defined(WOLFSSL_GENSEED_FORTEST) || defined(WOLFSSL_CHIBIOS) || \
+      defined(WOLFSSL_CONTIKI)  || defined(WOLFSSL_AZSPHERE)
+
+    /* these platforms do not have a default random seed and
+       you'll need to implement your own wc_GenerateSeed or define via
+       CUSTOM_RAND_GENERATE_BLOCK */
+
+    #define USE_TEST_GENSEED
+
 #elif defined(NO_DEV_RANDOM)
 
     #error "you need to write an os specific wc_GenerateSeed() here"