firmware: Refer to the co-maintained linux-firmware.git repository

David and I are sharing maintenance of this repository.  Patches
should be sent to both of us.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

firmware/README.AddingFirmware

@@ -12,7 +12,7 @@ here.
 This directory is _NOT_ for adding arbitrary new firmware images. The
 place to add those is the separate linux-firmware repository:
 
-    git://git.kernel.org/pub/scm/linux/kernel/git/dwmw2/linux-firmware.git
+    git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
 
 That repository contains all these firmware images which have been
 extracted from older drivers, as well various new firmware images which
@@ -22,6 +22,7 @@ been permitted to redistribute under separate cover.
 To submit firmware to that repository, please send either a git binary
 diff or preferably a git pull request to:
       David Woodhouse <dwmw2@infradead.org>
+      Ben Hutchings <ben@decadent.org.uk>
 
 Your commit should include an update to the WHENCE file clearly
 identifying the licence under which the firmware is available, and