Avoid trashing IP fragments:
- Only enable UDP/TCP hardware checksums if CSUM_UDP or CSUM_TCP is set.
- Only enable IP hardware checksums if CSUM_IP is set.

PR:		kern/180430
Submitted by:	Meny Yossefi <menyy@mellanox.com>
MFC after:	1 week
Set the device description after we call uart_probe(). In uart_probe()
we call device-specific probe functions, which can (and typically will)
set the device description based on low-level device probe information.
In the end we never actually used the device description that we so
carefully maintained in the PCI match table. By setting the device
description after we call uart_probe(), we'll print the more user-
friendly description by default.