buildsys: Remove support for 32-bit MIPS hosts

Stop detecting 32-bit MIPS host as supported, update the
deprecation document. See previous commit for rationale.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20251009195210.33161-8-philmd@linaro.org>

configure

@@ -404,8 +404,6 @@ elif check_define _ARCH_PPC ; then
 elif check_define __mips__ ; then
   if check_define __mips64 ; then
     cpu="mips64"
-  else
-    cpu="mips"
   fi
 elif check_define __s390__ ; then
   if check_define __s390x__ ; then
@@ -473,11 +471,6 @@ case "$cpu" in
     host_arch=mips
     linux_arch=mips
     ;;
-  mips*)
-    cpu=mips
-    host_arch=mips
-    linux_arch=mips
-    ;;
 
   ppc)
     host_arch=ppc