Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Make mvs_if.c to not be always linked statically into the kernel.
Link it same way as mvs.c.

Import mvs(4) - Marvell 88SX50XX/88SX60XX/88SX70XX/SoC SATA controllers
driver for CAM ATA subsystem. This driver supports same hardware as
atamarvell, ataadaptec and atamvsata drivers from ata(4), but provides
many additional features, such as NCQ, PMP, etc.