Consolidate conversions of is-board-platform(2)

mk2rbc implements conversions for both
is-board-platform(-in-list) and
is-board-platform(-in-list)2. The conversions
are not the same despite the functions being the
same. Make them convert to the same thing.

Bug: 201477826
Test: go test
Change-Id: I688a2f6114e1688c713e42f0f9229cbc5ee6a917
diff --git a/mk2rbc/mk2rbc_test.go b/mk2rbc/mk2rbc_test.go
index 1ba273b..22117c1 100644
--- a/mk2rbc/mk2rbc_test.go
+++ b/mk2rbc/mk2rbc_test.go
@@ -598,9 +598,9 @@
 
 def init(g, handle):
   cfg = rblf.cfg(handle)
-  if g.get("TARGET_BOARD_PLATFORM", "") in ["msm8998"]:
+  if rblf.board_platform_in(g, "msm8998"):
     pass
-  elif g.get("TARGET_BOARD_PLATFORM", "") != "copper":
+  elif not rblf.board_platform_is(g, "copper"):
     pass
   elif g.get("TARGET_BOARD_PLATFORM", "") not in g["QCOM_BOARD_PLATFORMS"]:
     pass