hvcs: Get reference to tty in remove

Grab a reference to the tty when removing the hvcs to ensure
it does not get freed unexpectedly.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20230203155802.404324-4-brking@linux.vnet.ibm.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>