[config] Suppress implicit fallthrough

Change-Id: I972de9f07f74b57f925d5611f205b23eddece739
diff --git a/embdrv/sbc/BUILD.gn b/embdrv/sbc/BUILD.gn
index 0baff2d..653037a 100644
--- a/embdrv/sbc/BUILD.gn
+++ b/embdrv/sbc/BUILD.gn
@@ -18,6 +18,13 @@
   include_dirs = [ "decoder/include" ]
 }
 
+config("sbc_warnings") {
+  cflags = [
+    "-Wno-conversion",
+    "-Wno-implicit-fallthrough",
+  ]
+}
+
 source_set("sbc_decoder") {
   sources = [
     "decoder/srce/alloc.c",
@@ -36,14 +43,12 @@
     "decoder/srce/synthesis-sbc.c",
   ]
 
+  configs += [ ":sbc_warnings" ]
   public_configs = [ ":sbc_decoder_includes_config" ]
 
   # TODO(46738): UBSan has found an instance of undefined behavior in this target.
   # Disable UBSan for this target temporarily until it is migrated into CI/CQ.
   configs += [ "//build/config:temporarily_disable_ubsan_do_not_use" ]
-
-  # TODO(fxb/58162): delete the below and fix compiler warnings
-  configs += [ "//build/config:Wno-conversion" ]
 }
 
 config("sbc_encoder_includes_config") {
@@ -62,14 +67,12 @@
     "encoder/srce/sbc_packing.c",
   ]
 
+  configs += [ ":sbc_warnings" ]
   public_configs = [ ":sbc_encoder_includes_config" ]
 
   # TODO(46738): UBSan has found an instance of undefined behavior in this target.
   # Disable UBSan for this target temporarily until it is migrated into CI/CQ.
   configs += [ "//build/config:temporarily_disable_ubsan_do_not_use" ]
-
-  # TODO(fxb/58162): delete the below and fix compiler warnings
-  configs += [ "//build/config:Wno-conversion" ]
 }
 
 static_library("sbc") {