gnu: Remove duplicated emacs-csv-mode.

It was first added in 9faa46ee48, and then again
in 8bc8efc753.

* gnu/packages/emacs.scm (emacs-csv-mode): Remove duplicated package
definition.

gnu/packages/emacs.scm

@@ -9653,26 +9653,6 @@ buffer.")
 downloading manager for Emacs.")
       (license license:gpl3+))))
 
-(define-public emacs-csv-mode
-  (package
-    (name "emacs-csv-mode")
-    (version "1.7")
-    (source
-     (origin
-       (method url-fetch)
-       (uri (string-append "http://elpa.gnu.org/packages/csv-mode-"
-                           version ".el"))
-       (sha256
-        (base32
-         "0r4bip0w3h55i8h6sxh06czf294mrhavybz0zypzrjw91m1bi7z6"))))
-    (build-system emacs-build-system)
-    (home-page "http://elpa.gnu.org/packages/csv-mode.html")
-    (synopsis "Major mode for editing comma or char separated values")
-    (description
-     "This package provides an Emacs CSV mode, a major mode for editing
-records in a generalized CSV (character-separated values) format.")
-    (license license:gpl3+)))
-
 (define-public emacs-helpful
   (package
     (name "emacs-helpful")