mpi3mr: Allow driver to be in-kenrel and add to GENERIC

Registered the mpi3mr driver source files in sys/conf/files, enabling it
to be compiled into the base kernel image. This matches the approach
used for existing Broadcom drivers such as mrsas, mps, and mpr.

Add mpi3mr to sys/conf/NOTES.

With this change, the mpi3mr driver will be built as part of the base
kernel, allowing automatic loading during boot when supported hardware
is detected.

Below changes are suggested by chs@:
- Corrected the file name typo mistake in /sys/conf/files from
  mpi3mr_app.c.c to mpi3mr_app.c
- Added mpi3mr driver entries in "sys/amd64/conf/GENERIC" and
  "sys/i386/conf/GENERIC"

Reviewed by:	ssaxena, chs, imp
Differential Revision:	https://reviews.freebsd.org/D49754

sys/amd64/conf/GENERIC

@@ -145,6 +145,7 @@ device		isp			# Qlogic family
 device		mpt			# LSI-Logic MPT-Fusion
 device		mps			# LSI-Logic MPT-Fusion 2
 device		mpr			# LSI-Logic MPT-Fusion 3
+device		mpi3mr			# LSI-Logic MPT-Fusion 4
 device		sym			# NCR/Symbios Logic
 device		isci			# Intel C600 SAS controller
 device		ocs_fc			# Emulex FC adapters

sys/conf/NOTES

@@ -1592,6 +1592,7 @@ envvar		hint.isp.0.topology="nport-only"
 envvar		hint.isp.0.portwnn="w50000000aaaa0000"
 envvar		hint.isp.0.nodewnn="w50000000aaaa0001"
 device		ispfw
+device		mpi3mr			# LSI-Logic MPT-Fusion 4
 device		mpr			# LSI-Logic MPT-Fusion 3
 device		mps			# LSI-Logic MPT-Fusion 2
 device		mpt			# LSI-Logic MPT-Fusion

sys/conf/files

@@ -2465,6 +2465,11 @@ dev/mrsas/mrsas.c		optional mrsas
 dev/mrsas/mrsas_cam.c		optional mrsas
 dev/mrsas/mrsas_ioctl.c		optional mrsas
 dev/mrsas/mrsas_fp.c		optional mrsas
+dev/mpi3mr/mpi3mr.c		optional mpi3mr
+dev/mpi3mr/mpi3mr_pci.c		optional mpi3mr
+dev/mpi3mr/mpi3mr_app.c		optional mpi3mr
+dev/mpi3mr/mpi3mr_cam.c		optional mpi3mr \
+	compile-with "${LINUXKPI_C}"
 dev/msk/if_msk.c		optional msk
 dev/mvs/mvs.c			optional mvs
 dev/mvs/mvs_if.m		optional mvs