build-appliance-image: Update to kirkstone head revision

(From OE-Core rev: 1efbe1004bc82e7c14c1e8bd4ce644f5015c3346)

Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/recipes-core/images/build-appliance-image_15.0.0.bb

@@ -24,7 +24,7 @@ IMAGE_FSTYPES = "wic.vmdk wic.vhd wic.vhdx"
 
 inherit core-image setuptools3
 
-SRCREV ?= "285e878650919844f8194c9b5c2fc034b019c4a3"
+SRCREV ?= "91484dd59353b085bb6c463da9ecd5d2b51d8e64"
 SRC_URI = "git://git.yoctoproject.org/poky;branch=kirkstone \
            file://Yocto_Build_Appliance.vmx \
            file://Yocto_Build_Appliance.vmxf \