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

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>