rx: switch boards to "default y"

Some targets use "default y" for boards to filter out those that require
TCG.  For consistency we are switching all other targets to do the same.
Continue with RX.

No changes to generated config-devices.mak file.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

.gitlab-ci.d/buildtest.yml

@@ -649,7 +649,7 @@ build-tci:
 
 # Check our reduced build configurations
 # requires libfdt: aarch64, arm, i386, loongarch64, microblaze, microblazeel,
-#   mips64el, or1k, ppc, ppc64, riscv32, riscv64, x86_64
+#   mips64el, or1k, ppc, ppc64, riscv32, riscv64, rx, x86_64
 # does not build without boards: i386, loongarch64, x86_64
 build-without-defaults:
   extends: .native_build_job_template

configs/devices/rx-softmmu/default.mak

@@ -1,3 +1,4 @@
 # Default configuration for rx-softmmu
 
-CONFIG_RX_GDBSIM=y
+# Boards are selected by default, uncomment to keep out of the build.
+# CONFIG_RX_GDBSIM=n

hw/rx/Kconfig

@@ -7,4 +7,6 @@ config RX62N_MCU
 
 config RX_GDBSIM
     bool
+    default y
+    depends on RX
     select RX62N_MCU