cores/microwatt: remove outdated patch.

The demo README provides an URL to a fork with experimental support for
PowerFV.

cores/microwatt/0001-WIP.patch

@@ -1,35 +0,0 @@
-From 43c771bbffb891c6c8b1f9a4b4dea173a1830ef3 Mon Sep 17 00:00:00 2001
-From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Nguyen?= <jf@jfng.fr>
-Date: Wed, 6 Apr 2022 14:14:57 +0200
-Subject: [PATCH] WIP
-
----
- core.vhdl | 5 ++++-
- 1 file changed, 4 insertions(+), 1 deletion(-)
-
-diff --git a/core.vhdl b/core.vhdl
-index cf730c5..3fb54b8 100644
---- a/core.vhdl
-+++ b/core.vhdl
-@@ -49,7 +49,9 @@ entity core is
- 
- 	ext_irq		: in std_ulogic;
- 
--	terminated_out   : out std_logic
-+	terminated_out   : out std_logic;
-+
-+        complete_out : out instr_tag_t
-         );
- end core;
- 
-@@ -187,6 +189,7 @@ architecture behave of core is
- begin
- 
-     core_rst <= dbg_core_rst or rst;
-+    complete_out <= complete;
- 
-     resets: process(clk)
-     begin
--- 
-2.35.1
-