gitignore: add tags files and Vim swap file

Signed-off-by: Markus Heidelberg <markus.heidelberg@web.de>

.gitignore

@@ -11,6 +11,7 @@
 *.a
 *.o
 *~
+*.swp
 *.patch
 
 #
@@ -49,6 +50,10 @@ series
 # cscope files
 cscope.*
 
+# tags files
+/ctags
+/etags
+
 # OneNAND IPL files
 /onenand_ipl/onenand-ipl*
 /onenand_ipl/board/*/onenand*