fw: Rename FIRMWARE_SOURCES, use globbing

The symbol is only used for the check targets (with clangd and splint)
and doesn't include all the source files in the firmware. Let's just
use globbing instead.

hw/application_fpga/Makefile

@@ -60,6 +60,7 @@ CFLAGS = \
 	-Wall \
 	-Wpedantic \
 	-Wno-language-extension-token \
+	-Wextra \
 	-flto \
 	-g \
 	-I $(LIBDIR)/include \
@@ -136,11 +137,8 @@ FIRMWARE_OBJS = \
 	$(P)/fw/tk1/preload_app.o \
 	$(P)/fw/tk1/mgmt_app.o
 
-FIRMWARE_SOURCES = \
-	$(P)/fw/tk1/main.c \
-	$(P)/fw/tk1/proto.c \
-	$(P)/fw/tk1/blake2s/blake2s.c \
-	$(P)/fw/tk1/syscall_handler.c
+CHECK_SOURCES = \
+	$(P)/fw/tk1/*.[ch]
 
 TESTFW_OBJS = \
 	$(P)/fw/testfw/main.o \
@@ -219,7 +217,7 @@ compile_commands.json:
 
 .PHONY: check
 check:
-	clang-tidy -header-filter=.* -checks=cert-* $(FIRMWARE_SOURCES) -- $(CFLAGS)
+	clang-tidy -header-filter=.* -checks=cert-* $(CHECK_SOURCES) -- $(CFLAGS)
 
 .PHONY: splint
 splint:
@@ -235,7 +233,7 @@ splint:
 		-unreachable \
 		-unqualifiedtrans \
 		-fullinitblock \
-		$(FIRMWARE_SOURCES)
+		$(CHECK_SOURCES)
 
 testfw.elf: tkey-libs $(TESTFW_OBJS) $(P)/fw/tk1/firmware.lds
 	$(CC) $(CFLAGS) $(TESTFW_OBJS) $(LDFLAGS) -o $@ > $(basename $@).map