qemu-char: remove dead/confusing logic with nb_stdio_clients

qemu-char: remove dead/confusing logic with nb_stdio_clients

This code is very old dating back to 2007.  What is puzzling is that
STDIO_MAX_CLIENTS was always #define to 1 meaning that all of the code to deal
with more than one client was unreachable.

Just remove the whole mess of it.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Message-id: d276bccdbf4e7463020c5f539f61ae3bfbc88d1d.1362505276.git.amit.shah@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>