microblaze: 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 Microblaze.

No changes to generated config-devices.mak file.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/.gitlab-ci.d/buildtest.yml b/.gitlab-ci.d/buildtest.yml
index a91e8d3..e2e92f2 100644
--- a/.gitlab-ci.d/buildtest.yml
+++ b/.gitlab-ci.d/buildtest.yml
@@ -648,7 +648,8 @@
     - make check-tcg
 
 # Check our reduced build configurations
-# requires libfdt: aarch64, arm, i386, loongarch64, x86_64
+# requires libfdt: aarch64, arm, i386, loongarch64, microblaze, microblazeel,
+#   x86_64
 # does not build without boards: i386, loongarch64, x86_64
 build-without-defaults:
   extends: .native_build_job_template
diff --git a/configs/devices/microblaze-softmmu/default.mak b/configs/devices/microblaze-softmmu/default.mak
index db8c6e4..583e395 100644
--- a/configs/devices/microblaze-softmmu/default.mak
+++ b/configs/devices/microblaze-softmmu/default.mak
@@ -1,7 +1,6 @@
 # Default configuration for microblaze-softmmu
 
-# Boards:
-#
-CONFIG_PETALOGIX_S3ADSP1800=y
-CONFIG_PETALOGIX_ML605=y
-CONFIG_XLNX_ZYNQMP_PMU=y
+# Boards are selected by default, uncomment to keep out of the build.
+# CONFIG_PETALOGIX_S3ADSP1800=n
+# CONFIG_PETALOGIX_ML605=n
+# CONFIG_XLNX_ZYNQMP_PMU=n
diff --git a/hw/microblaze/Kconfig b/hw/microblaze/Kconfig
index e2697ce..d78ba84 100644
--- a/hw/microblaze/Kconfig
+++ b/hw/microblaze/Kconfig
@@ -1,5 +1,7 @@
 config PETALOGIX_S3ADSP1800
     bool
+    default y
+    depends on MICROBLAZE
     select PFLASH_CFI01
     select XILINX
     select XILINX_AXI
@@ -8,6 +10,8 @@
 
 config PETALOGIX_ML605
     bool
+    default y
+    depends on MICROBLAZE
     select PFLASH_CFI01
     select SERIAL
     select SSI_M25P80
@@ -18,4 +22,6 @@
 
 config XLNX_ZYNQMP_PMU
     bool
+    default y
+    depends on MICROBLAZE
     select XLNX_ZYNQMP