net: hdlc_x25: Return meaningful error code in x25_open

It's not meaningful to pass on LAPB error codes to HDLC code or other
parts of the system, because they will not understand the error codes.

Instead, use system-wide recognizable error codes.

Fixes: f362e5fe ("wan/hdlc_x25: make lapb params configurable")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Acked-by: Martin Schiller <ms@dev.tdt.de>
Link: https://lore.kernel.org/r/20210203071541.86138-1-xie.he.0141@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>