poky: reset subtree on master HEAD(a88251b3e7)

As part of the last subtree update, I used master-next as the
subtree basis because there was a fix we needed in order to get QEMU
to pass.  I didn't realize that master-next deviated (because they use
to just have short-term patches in it).  Reset the content to the same
fix but from the master branch.

Change-Id: Ic7d2f0ac42e9da3eb263586b26ba56d8798d5bcf
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/poky/meta/recipes-core/images/build-appliance-image_15.0.0.bb b/poky/meta/recipes-core/images/build-appliance-image_15.0.0.bb
index 6e222df..4cf5551 100644
--- a/poky/meta/recipes-core/images/build-appliance-image_15.0.0.bb
+++ b/poky/meta/recipes-core/images/build-appliance-image_15.0.0.bb
@@ -26,7 +26,7 @@
 
 REQUIRED_DISTRO_FEATURES += "xattr"
 
-SRCREV ?= "cf69c6843fb62ab2ebee361f3d1a1141f1a6b01a"
+SRCREV ?= "17723c6e34096a53fb186cc70cfc604bb30da8b9"
 SRC_URI = "git://git.yoctoproject.org/poky;branch=master \
            file://Yocto_Build_Appliance.vmx \
            file://Yocto_Build_Appliance.vmxf \