net: usb: pegasus: fix improper read if get_registers() fail

commit 224c0497 upstream.

get_registers() may fail with -ENOMEM and in this
case we can read a garbage from the status variable tmp.

Reported-by:  <syzbot+3499a83b2d062ae409d4@syzkaller.appspotmail.com>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>