Fix typo in yasm dummy DEPS.

Was specifying jsoncpp_revision instead of patched_yasm_revision.

Bug: 1017514
Change-Id: Ib16f9bb28843c17c24fabcf344fdaf50846b4a5e
Tbr: dpranke@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1882087Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709745}

third_party/yasm/DEPS

@@ -14,5 +14,5 @@ vars = {
 }
 
 deps = {
-  'source/patched-yasm': '{chromium_git}/chromium/deps/yasm/patched-yasm.git@{jsoncpp_revision}'
+  'source/patched-yasm': '{chromium_git}/chromium/deps/yasm/patched-yasm.git@{patched_yasm_revision}'
 }