Documentation/SubmittingPatches: unify whitespace/tabs for the DCO

The Developers Certificate of Origin has a mixture of tabs and white
spaces which is annoying to view if your editor explicitly views white
space characters.

Also remove any trailing white spaces found in the file.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index 1fa1caa..1671ce3 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -223,9 +223,9 @@
 
 
 Linus Torvalds is the final arbiter of all changes accepted into the
-Linux kernel.  His e-mail address is <torvalds@linux-foundation.org>. 
+Linux kernel.  His e-mail address is <torvalds@linux-foundation.org>.
 He gets a lot of e-mail, so typically you should do your best to -avoid-
-sending him e-mail. 
+sending him e-mail.
 
 Patches which are bug fixes, are "obvious" changes, or similarly
 require little discussion should be sent or CC'd to Linus.  Patches
@@ -387,11 +387,11 @@
             person who certified (a), (b) or (c) and I have not modified
             it.
 
-	(d) I understand and agree that this project and the contribution
-	    are public and that a record of the contribution (including all
-	    personal information I submit with it, including my sign-off) is
-	    maintained indefinitely and may be redistributed consistent with
-	    this project or the open source license(s) involved.
+        (d) I understand and agree that this project and the contribution
+            are public and that a record of the contribution (including all
+            personal information I submit with it, including my sign-off) is
+            maintained indefinitely and may be redistributed consistent with
+            this project or the open source license(s) involved.
 
 then you just add a line saying
 
@@ -401,7 +401,7 @@
 
 Some people also put extra tags at the end.  They'll just be ignored for
 now, but you can do this to mark internal company procedures or just
-point out some special detail about the sign-off. 
+point out some special detail about the sign-off.
 
 If you are a subsystem or branch maintainer, sometimes you need to slightly
 modify patches you receive in order to merge them, because the code is not