tls_provider_init(): Rename prov_ctx to xor_prov_ctx to clarify

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
(Merged from #24103)

(cherry picked from commit 3de3d48)

test/tls-provider.c

@@ -3220,12 +3220,12 @@ int tls_provider_init(const OSSL_CORE_HANDLE *handle,
     OSSL_LIB_CTX *libctx = OSSL_LIB_CTX_new_from_dispatch(handle, in);
     OSSL_FUNC_core_obj_create_fn *c_obj_create= NULL;
     OSSL_FUNC_core_obj_add_sigid_fn *c_obj_add_sigid= NULL;
-    PROV_XOR_CTX *prov_ctx = xor_newprovctx(libctx);
+    PROV_XOR_CTX *xor_prov_ctx = xor_newprovctx(libctx);
 
-    if (libctx == NULL || prov_ctx == NULL)
+    if (libctx == NULL || xor_prov_ctx == NULL)
         goto err;
 
-    *provctx = prov_ctx;
+    *provctx = xor_prov_ctx;
 
     /*
      * Randomise the group_id and code_points we're going to use to ensure we
@@ -3279,7 +3279,7 @@ int tls_provider_init(const OSSL_CORE_HANDLE *handle,
     return 1;
 
 err:
-    OPENSSL_free(prov_ctx);
+    OPENSSL_free(xor_prov_ctx);
     *provctx = NULL;
     OSSL_LIB_CTX_free(libctx);
     return 0;