Code optimization and style fixes

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/programs/x509/cert_req.c b/programs/x509/cert_req.c
index 8baca81..2f7126b 100644
--- a/programs/x509/cert_req.c
+++ b/programs/x509/cert_req.c
@@ -169,7 +169,6 @@
     mbedtls_ctr_drbg_context ctr_drbg;
     const char *pers = "csr example app";
     mbedtls_x509_san_list *cur, *prev;
-    uint8_t ip[4];
 
     /*
      * Set to sane values
@@ -220,6 +219,8 @@
             prev = NULL;
 
             while (q != NULL) {
+                uint8_t ip[4] = { 0 };
+
                 if ((r = strchr(q, ';')) != NULL) {
                     *r++ = '\0';
                 }