rgw/rgw_user.h: remove twice initialized purge_keys

Remove twice initialized purge_keys from RGWUserAdminOpState();

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
rgw/rgw_user.cc: reduce scope of variable

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>