gateware/build: Update submodule

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: Ib61dac16fc2399b8b357ec8ba8e7f19e2c79b4d8
diff --git a/gateware/build b/gateware/build
index f281c76..87481ca 160000
--- a/gateware/build
+++ b/gateware/build
@@ -1 +1 @@
-Subproject commit f281c76d9610564d2100221ff05b2927e8aec6e6
+Subproject commit 87481ca25e6ebcb6cb2a5a1ca6fe7386e2ea9ed8