meta-facebook: prep for new override syntax

Ran `scripts/contrib/convert-overrides.py` from upstream Yocto and
fixed up a few by hand that were missed.

Tested: Built bletchley and tiogapass.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I0489ba007132901697e4ef1a29b03a3591b3ee3b
diff --git a/meta-facebook/meta-tiogapass/conf/machine/tiogapass.conf b/meta-facebook/meta-tiogapass/conf/machine/tiogapass.conf
index 1e6ee08..deaf0f2 100644
--- a/meta-facebook/meta-tiogapass/conf/machine/tiogapass.conf
+++ b/meta-facebook/meta-tiogapass/conf/machine/tiogapass.conf
@@ -9,5 +9,5 @@
 
 SERIAL_CONSOLES = "57600;ttyS4"
 
-PREFERRED_PROVIDER_virtual/obmc-host-ctl ?= ""
+PREFERRED_PROVIDER:virtual/obmc-host-ctl ?= ""
 FLASH_SIZE = "32768"