Decrease logging severity when adding a device or reading config table.

Decrease logging severity when adding a device or reading config table.

In PR 243056 a user reports some spam from smartpqi(4).  In particular,
the driver warns about an unrecognized PQI_CONF_TABLE_SECTION_SOFT_RESET
section (not yet defined in the driver, but handled in Linux), but this
doesn't cause any problems.  The Linux driver also does not warn about
unrecognized sections.

Also do not log a warning when a device is added, since this is routine.
Lower severity to DISC, to match pqisrc_remove_device().

PR:		243056
Reviewed by:	sbruno
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23023