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/classes-global/sstate.bbclass b/poky/meta/classes-global/sstate.bbclass
index 96655ff..04539bb 100644
--- a/poky/meta/classes-global/sstate.bbclass
+++ b/poky/meta/classes-global/sstate.bbclass
@@ -4,7 +4,7 @@
 # SPDX-License-Identifier: MIT
 #
 
-SSTATE_VERSION = "11"
+SSTATE_VERSION = "12"
 
 SSTATE_ZSTD_CLEVEL ??= "8"