meta-phosphor: mmc-init: Fix creation of critical directories

`mkdir $fslist` is responsible for creating all the critical mount-point
directories for a functioning Linux userspace, such as `/dev`, `/proc`
and `/sys`.  2345ace954c2 ("meta-phosphor: phosphor-mmc-init: fix
shellcheck") prevented their existence by instead creating a single
directory named "proc sys dev run":

```
~ # ls -1
bin
dev
etc
init
lib
mnt
proc sys dev run
root
run
sbin
usr
var
```

The lack of directories lead to the inability to mount the required
filesystems, with the boot process stalling at an initrd shell prompt:

```
[    1.224302] Freeing initrd memory: 3272K
[    1.265274] Freeing unused kernel image (initmem) memory: 1024K
[    1.291134] Checked W+X mappings: passed, no W+X pages found
[    1.291492] Run /init as init process
mount: mounting sys on sys failed: No such file or directory
mount: mounting proc on proc failed: No such file or directory
[    2.600405]  mmcblk0: p1 p2 p3 p4 p5 p6 p7
The operation has completed successfully.
Failed to parse kernel command line, ignoring: No such file or directory
Starting systemd-udevd version 253.1^
Running in chroot, ignoring request.
Running in chroot, ignoring request.
cat: can't open '/proc/cmdline': No such file or directory
[    2.706024] /dev/disk/by-partlabel/: Can't open blockdev
mount: mounting /dev/disk/by-partlabel/ on /mnt/rofs failed: No such file or directory
/bin/sh: can't access tty; job control turned off
~ #
```

Change-Id: Ie0821508ed7e141c89d7620a6ed0adc069f5c267
Fixes: 2345ace954c2 ("meta-phosphor: phosphor-mmc-init: fix shellcheck")
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/meta-phosphor/recipes-phosphor/initrdscripts/phosphor-mmc-init/mmc-init.sh b/meta-phosphor/recipes-phosphor/initrdscripts/phosphor-mmc-init/mmc-init.sh
index 12cf53a..c55977f 100644
--- a/meta-phosphor/recipes-phosphor/initrdscripts/phosphor-mmc-init/mmc-init.sh
+++ b/meta-phosphor/recipes-phosphor/initrdscripts/phosphor-mmc-init/mmc-init.sh
@@ -23,7 +23,13 @@
 rwfsdev="/dev/disk/by-partlabel/rwfs"
 
 cd /
-mkdir -p "$fslist"
+
+# We want to make all the directories in $fslist, not one directory named by
+# concatonating the names with spaces
+#
+# shellcheck disable=SC2086
+mkdir -p $fslist
+
 mount dev dev -tdevtmpfs
 mount sys sys -tsysfs
 mount proc proc -tproc