hvc: haven: Prevent tty layer from closing SELF console

If HVC_HAVEN_CONSOLE is set, then kernel may be using the RM console for
printk. Thus, when userspace accesses the "self" console, we should not
be re-opening or closing this console along with userspace. In open
case, it is incorrect to open console when it is already open and may
result in an error from RM. In close case, this could cause printk
messages to be lost.

Change-Id: Ie73cc0d401c9feb45f952a3dcaaf7ec8cbfccbc9
Signed-off-by: Elliot Berman <eberman@codeaurora.org>