MAINTAINERS: update mailing list address for NTB subsystem

NTB mailing list is moving from linux-ntb@googlegroups.com to
ntb@lists.linux.dev in order to get better archive and lore support.
Update all entries in MAINTAINERS.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>