jsm: correctly support multiple 4/8-port boards

If there are more then one 4/8-port board jsm_uart_port_init
allocate a line numbers of the second and further boards
from range of previous one.

This patch fixed the problem.

Signed-off-by: Alexander Y. Fomichev <git.user@gmail.com>
[printks fixed to add jsm: ]

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>