Merged uSD driver into unified tool build, completed conversion of tools.

- atusd/tools/lib/atusd.c: moved to tools/lib/
- atusd/tools/lib/atusd.h: removed, we can now use tools/include/atspi.h
- tools/lib/atusd.c: added copyright header
- tools/lib/atusd.c: updated for driver API
- tools/lib/Makefile: added atusd.o
- tools/Makefile.common: moved common elements from all other makefiles in
  tools/*/ here
- tools/Makefile.common: added target-specific compiler and flags
- tools/atspi-id/Makefile, tools/atspi-reset/Makefile,
  tools/atspi-rssi/Makefile, tools/atspi-trim/Makefile,
  tools/atspi-txrx/Makefile, tools/lib/Makefile: used Makefile.common
- tools/lib/Makefile: differentiate USB and uSD build
- tools/atspi-id/atspi-id.c, tools/atspi-reset/atspi-reset.c,
  tools/atspi-rssi/atspi-rssi.c, tools/atspi-trim/atspi-trim.c,
  tools/atspi-txr/atspi-txr.c: updated for driver-agnostic API
- tools/atspi-id/atspi-id.c, tools/atspi-reset/atspi-reset.c,
  tools/atspi-rssi/atspi-rssi.c, tools/atspi-trim/atspi-trim.c,
  tools/atspi-txr/atspi-txr.c: corrected AF86RF230 typo in title
- tools/include/atspi.h, tools/lib/atspi.c, tools/lib/driver.c,
  tools/lib/atusb.c: brought back support for atspi_error and
  atspi_clear_error
- tools/atspi-id/atspi-id.c (atspi_get_protocol): renamed to get_protocol,
  to make it clear that it's not from libatspi
- tools/atspi-id/atspi-id.c (atspi_get_build): renamed to get_build, to
  make it clear that it's not from libatspi
- tools/include/atspi.h, tools/lib/atspi.c (atspi_usb_handle): new function
  to obtain a driver's USB device handle (or NULL if the driver doesn't use
  USB)

tools/atspi-reset/atspi-reset.c

@@ -1,5 +1,5 @@
 /*
- * atspi-rssi/atspi-rssi.c - ben-wpan AF86RF230 spectrum scan
+ * atspi-rssi/atspi-rssi.c - ben-wpan AT86RF230 spectrum scan
  *
  * Written 2010 by Werner Almesberger
  * Copyright 2010 Werner Almesberger
@@ -14,7 +14,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <usb.h>
 
 #include "atspi.h"
 
@@ -32,7 +31,7 @@ static void usage(const char *name)
 
 int main(int argc, const char **argv)
 {
-	usb_dev_handle *dev;
+	struct atspi_dsc *dsc;
 	int txrx = 1;
 
 	switch (argc) {
@@ -49,14 +48,14 @@ int main(int argc, const char **argv)
 		usage(*argv);
 	}
 
-	dev = atspi_open();
-	if (!dev)
+	dsc = atspi_open();
+	if (!dsc)
 		return 1;
 
         if (txrx)
-                atspi_reset_rf(dev);
+                atspi_reset_rf(dsc);
         else
-                atspi_reset(dev);
+                atspi_reset(dsc);
         return 0;
 }