meta-facebook: add tmux to all images

Bletchley PE requested we add tmux to the images.

In order for tmux to work we also need to generate the en-us locale
because tmux requires UTF-8 locale information.  Add this to all our
images as well (it is disabled in meta-phosphor to save space).

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I40b92ea975b64e364003d542d71cb0103df34cfe
diff --git a/meta-facebook/recipes-phosphor/images/fb-phosphor-image.inc b/meta-facebook/recipes-phosphor/images/fb-phosphor-image.inc
index 17cc928..b26611a 100644
--- a/meta-facebook/recipes-phosphor/images/fb-phosphor-image.inc
+++ b/meta-facebook/recipes-phosphor/images/fb-phosphor-image.inc
@@ -5,8 +5,11 @@
         bb.utils.contains('MACHINE_FEATURES', 'tpm2', 'packagegroup-security-tpm2 libtss2-tcti-device', '', d), \
         '', d)} \
     curl \
+    tmux \
     "
 
+IMAGE_LINGUAS="en-us"
+
 OBMC_IMAGE_EXTRA_INSTALL:append:mf-fb-secondary-emmc = " emmc-init"
 
 include recipes-phosphor/images/fb-${MACHINE}-phosphor-image.inc