USB: tools: Add a Makefile

Build USB tools easier.
Signed-off-by: NDavidlohr Bueso <dave@gnu.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

tools/usb/Makefile

+# Makefile for USB tools
+
+CC = $(CROSS_COMPILE)gcc
+PTHREAD_LIBS = -lpthread
+WARNINGS = -Wall -Wextra
+CFLAGS = $(WARNINGS) -g $(PTHREAD_LIBS)
+
+all: testusb ffs-test
+%: %.c
+	$(CC) $(CFLAGS) -o $@ $^
+
+clean:
+	$(RM) testusb ffs-test