char: Remove special init_reset handling

The initial_reset sent to chardevs doesn't do much other than setting
a bool to true. Char devices are interested in the open event and
that gets sent whenever the device is opened.

Moreover, the reset logic breaks as and when qemu's bh scheduling
changes.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>