[doc] Avoid trailing whitespace in auto-generated reggen pages

Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>
diff --git a/util/reggen/reg_html.css b/util/reggen/reg_html.css
index 4cb48ed..997fabc 100644
--- a/util/reggen/reg_html.css
+++ b/util/reggen/reg_html.css
@@ -6,7 +6,7 @@
 table.regpic {
     width: 95%;
     border-collapse: collapse;
-    margin-left:auto; 
+    margin-left:auto;
     margin-right:auto;
     table-layout:fixed;
 }
@@ -15,7 +15,7 @@
     border: 1px solid black;
     width: 80%;
     border-collapse: collapse;
-    margin-left:auto; 
+    margin-left:auto;
     margin-right:auto;
     table-layout:auto;
 }