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/include/atspi.h

@@ -19,12 +19,14 @@
 struct atspi_dsc;
 
 
-int atspi_error(void);
-int atspi_clear_error(void);
+void *atspi_usb_handle(struct atspi_dsc *dsc); /* hack for atspi-id */
 
 struct atspi_dsc *atspi_open(void);
 void atspi_close(struct atspi_dsc *dsc);
 
+int atspi_error(struct atspi_dsc *dsc);
+int atspi_clear_error(struct atspi_dsc *dsc);
+
 void atspi_reset(struct atspi_dsc *dsc);
 void atspi_reset_rf(struct atspi_dsc *dsc);