build-appliance-image: Update to kirkstone head revision

(From OE-Core rev: a744a897f0ea7d34c31c024c13031221f9a85f24)

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 ?= "387d01b0a46bf0adb3f4cb2188299f88ac58db2f"
+SRCREV ?= "f91fefe108568a1587c804c9ebc857a6fe7d8a33"
 SRC_URI = "git://git.yoctoproject.org/poky;branch=kirkstone \
            file://Yocto_Build_Appliance.vmx \
            file://Yocto_Build_Appliance.vmxf \