scripts/Makefile.extrawarn: Silence more DTC warnings

While our "extrawarns" logic has gotten out of sync with upstream
Kbuild, for now lets start by bringing in the latest set of DTC_FLAGS
from the Linux Kernel 5.0 to match their behavior in silencing warnings
from dtc.

Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 7ed520f..1105c76 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -74,5 +74,7 @@
 DTC_FLAGS += -Wno-pci_bridge
 DTC_FLAGS += -Wno-pci_device_bus_num
 DTC_FLAGS += -Wno-pci_device_reg
+DTC_FLAGS += -Wno-avoid_unnecessary_addr_size
+DTC_FLAGS += -Wno-alias_paths
 
 endif