rt2870sta: Use latest firmware for RT3070 and RT3071

Ralink's original drivers for RT2800U-family chips used multiple
different versions of the firmware for different chips.  The rt2870sta
driver in staging was briefly converted to load different files for
different chips.  However, the current rt2870.bin provides 2 images
that are supposed to cover all of them, so:

- Replace rt3070.bin with a symlink.  The driver will use the first
  image and ignore the second.
- Replace rt3071.bin with a copy of the second image in the current
  rt2870.bin.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

WHENCE

@@ -1120,12 +1120,22 @@ This is a link to rt2860.bin for compatibility.
 Driver: rt2800usb - Ralink RT2870, RT3070, RT3071, RT3072, RT5370 wireless MACs
 
 File: rt2870.bin
+
+Licence: Redistributable. See LICENCE.ralink-firmware.txt for details
+
+Binary file supplied by Shiang Tu <shiang_tu@ralinktech.com>. Firmware Version 29
+
+--------------------------------------------------------------------------
+
+Driver: rt2870sta - Ralink RT2870, RT3070, RT3071 wireless MACs
+
 File: rt3070.bin
 File: rt3071.bin
 
 Licence: Redistributable. See LICENCE.ralink-firmware.txt for details
 
-Binary file supplied by Shiang Tu <shiang_tu@ralinktech.com>. Firmware Version 29
+rt3070.bin is a link to rt2870.bin for compatibility.
+rt3071.bin is a copy of bytes 4096-8191 of rt2870.bin for compatibility.
 
 --------------------------------------------------------------------------
 

rt3070.bin

@@ -0,0 +1 @@
+rt2870.bin