jsm: Remove the uart port on errors

If kzmalloc fails, the uart port is not removed causing a leak.
This patch just add another label that removes the uart when the
kzmalloc fails.

Signed-off-by: Breno Leitao <leitao@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>