Fix permissions on MySQL/MariaDB for Kodi

GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'password1';
GRANT ALL PRIVILEGES ON *.* TO 'xbmc'@'%' IDENTIFIED BY 'password2';
GRANT ALL PRIVILEGES ON *.* TO 'kodi'@'%' IDENTIFIED BY 'password3';
FLUSH PRIVILEGES;