target/nios2: Remove the deprecated Nios II target

The Nios II target is deprecated since v8.2 in commit 9997771bc1
("target/nios2: Deprecate the Nios II architecture").

Remove:
- Buildsys / CI infra
- User emulation
- System emulation (10m50-ghrd & nios2-generic-nommu machines)
- Tests

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Marek Vasut <marex@denx.de>
Message-Id: <20240327144806.11319-3-philmd@linaro.org>
diff --git a/.gitlab-ci.d/crossbuilds.yml b/.gitlab-ci.d/crossbuilds.yml
index 987ba96..47bdb99 100644
--- a/.gitlab-ci.d/crossbuilds.yml
+++ b/.gitlab-ci.d/crossbuilds.yml
@@ -167,7 +167,7 @@
     IMAGE: fedora-win64-cross
     EXTRA_CONFIGURE_OPTS: --enable-fdt=internal --disable-plugins
     CROSS_SKIP_TARGETS: alpha-softmmu avr-softmmu hppa-softmmu
-                        m68k-softmmu microblazeel-softmmu nios2-softmmu
+                        m68k-softmmu microblazeel-softmmu
                         or1k-softmmu rx-softmmu sh4eb-softmmu sparc64-softmmu
                         tricore-softmmu xtensaeb-softmmu
   artifacts: