Revert "initramfs: use mount.zfs instead of mount"

This broke mounting of snapshots on / for users.

See #9461 (comment) for more context.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #14908

contrib/initramfs/scripts/zfs

@@ -326,7 +326,7 @@ mount_fs()
 
 	# Need the _original_ datasets mountpoint!
 	mountpoint=$(get_fs_value "$fs" mountpoint)
-	ZFS_CMD="mount.zfs -o zfsutil"
+	ZFS_CMD="mount -o zfsutil -t zfs"
 	if [ "$mountpoint" = "legacy" ] || [ "$mountpoint" = "none" ]; then
 		# Can't use the mountpoint property. Might be one of our
 		# clones. Check the 'org.zol:mountpoint' property set in
@@ -343,7 +343,7 @@ mount_fs()
 			fi
 			# Don't use mount.zfs -o zfsutils for legacy mountpoint
 			if [ "$mountpoint" = "legacy" ]; then
-				ZFS_CMD="mount.zfs"
+				ZFS_CMD="mount -t zfs"
 			fi
 			# Last hail-mary: Hope 'rootmnt' is set!
 			mountpoint=""
@@ -914,7 +914,7 @@ mountroot()
 		echo "       not specified on the kernel command line."
 		echo ""
 		echo "Manually mount the root filesystem on $rootmnt and then exit."
-		echo "Hint: Try:  mount.zfs -o zfsutil ${ZFS_RPOOL-rpool}/ROOT/system $rootmnt"
+		echo "Hint: Try:  mount -o zfsutil -t zfs ${ZFS_RPOOL-rpool}/ROOT/system $rootmnt"
 		shell
 	fi