MT#55881 diff/15301.up: rename offset variable to support MariaDB >=10.6

Fixes:

| Applying revision script /usr/share/ngcp-db-schema/db_scripts/diff/15301.up: ERROR 1064 (42000) at line 14: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'offset int;
|     DECLARE chunk longblob;
|     DECLARE done int DEFAULT FALSE;
|
| ...' at line 4
| failed. :(

This is caused by MariaDB having "offset" as reserved word, quoting from
https://mariadb.com/kb/en/upgrading-from-mariadb-10-5-to-mariadb-10-6/:

| New reserved word: OFFSET. This can no longer be used as an identifier without being quoted.

Now that Debian/bookworm includes mariadb-server v10.6.10-1
we need to rename the variable.

Change-Id: I9db699ef60259411b8b79305f08179d4989edcd2

db_scripts/diff/15301.up

@@ -14,7 +14,7 @@ DELIMITER ;;
 CREATE PROCEDURE split_autoprov_firmware_data()
 BEGIN
 
-    DECLARE n_fw_id, chunk_size, offset int;
+    DECLARE n_fw_id, chunk_size, off_set int;
     DECLARE chunk longblob;
     DECLARE done int DEFAULT FALSE;
 
@@ -22,7 +22,7 @@ BEGIN
     DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
 
     SET chunk_size = 10485760;
-    SET offset = 1;
+    SET off_set = 1;
 
     OPEN x;
     x_main: LOOP
@@ -30,15 +30,15 @@ BEGIN
         IF done THEN
             LEAVE x_main;
         END IF;
-        SET offset = 1;
+        SET off_set = 1;
         x_chunk: LOOP
-            SELECT substr(data, offset, chunk_size) INTO chunk
+            SELECT substr(data, off_set, chunk_size) INTO chunk
               FROM autoprov_firmwares
              WHERE id = n_fw_id;
             IF LENGTH(chunk) > 0 THEN
                 INSERT INTO autoprov_firmwares_data (fw_id, data)
                     VALUES (n_fw_id, chunk);
-                SET offset = offset+chunk_size;
+                SET off_set = off_set+chunk_size;
             ELSE
                 LEAVE x_chunk;
             END IF;