build: add lpc source files

Add lpc arch specific source file implementations to Makefile.  They
were accidentally left off.

Change-Id: I377d524e863620db273a92a3b6178d8e7a18a12d
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index 7d94589..3d0d93c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -7,7 +7,9 @@
 	firmware_handler.cpp \
 	lpc_handler.cpp \
 	pci_handler.cpp \
-	file_handler.cpp
+	file_handler.cpp \
+	lpc_aspeed.cpp \
+	lpc_nuvoton.cpp
 libfirmwareblob_la_LDFLAGS = \
 	$(PHOSPHOR_LOGGING_LIBS) \
 	-version-info 0:0:0 -shared