qdev: Fix comment around qdev_init_nofail()

In previous life qdev_init_nofail() used to call hw_error() which
did register dump and other scary things.  Now it calls
error_report() and does a regular exit(1).  Fix the comment
to match reality.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>