[reggen] Remove leftover gpio prj hjson

Following 2608b59314c2a1ce746e915c55778980bea9853a this removes the prj
file after the data is already included in the main hjson.
Fixes #17204

Signed-off-by: Tobias Wölfel <tobias.woelfel@mailbox.org>

hw/ip/gpio/data/gpio.prj.hjson

diff --git a/hw/ip/gpio/data/gpio.prj.hjson b/hw/ip/gpio/data/gpio.prj.hjson
deleted file mode 100644
index 77264bb..0000000
--- a/hw/ip/gpio/data/gpio.prj.hjson
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright lowRISC contributors.
-// Licensed under the Apache License, Version 2.0, see LICENSE for details.
-// SPDX-License-Identifier: Apache-2.0
-
-{
-    name:               "gpio",
-    design_spec:        "../doc",
-    dv_doc:             "../doc/dv",
-    hw_checklist:       "../doc/checklist",
-    sw_checklist:       "/sw/device/lib/dif/dif_gpio",
-    revisions: [
-      {
-        version:            "1.0",
-        life_stage:         "L2",
-        design_stage:       "D3",
-        verification_stage: "V3",
-        commit_id:          "c1be7eb2b7265cd5ba6ceb026c28acf8e371151a",
-        notes:              "",
-      }
-      {
-        version:            "1.1",
-        life_stage:         "L1",
-        design_stage:       "D3",
-        verification_stage: "V2",
-        dif_stage:          "S2",
-        commit_id:          "9a2fd04f5e1f36128c858d6a1a7b06c34681337c"
-        notes:              ""
-      }
-    ]
-}