microblaze: adjust the help to the real behavior

[ Upstream commit bafcc61d ]

"make ARCH=microblaze help" mentions simpleImage.<dt>.unstrip,
but it is not a real Make target. It does not work because Makefile
assumes "system.unstrip" is the name of DT.

$ make ARCH=microblaze CROSS_COMPILE=microblaze-linux- simpleImage.system.unstrip
  [ snip ]
make[1]: *** No rule to make target 'arch/microblaze/boot/dts/system.unstrip.dtb', needed by 'arch/microblaze/boot/dts/system.dtb'.  Stop.
make: *** [Makefile;1060: arch/microblaze/boot/dts] Error 2
make: *** Waiting for unfinished jobs....

simpleImage.<dt> works like a phony target that generates multiple
images. Reflect the real behavior. I removed the DT directory path
information because it is already explained a few lines below.

While I am here, I deleted the redundant *_defconfig explanation.

The top-level Makefile caters to list available defconfig files:

  mmu_defconfig            - Build for mmu
  nommu_defconfig          - Build for nommu
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/microblaze/Makefile

@@ -91,11 +91,11 @@ define archhelp
   echo '* linux.bin    - Create raw binary'
   echo '  linux.bin.gz - Create compressed raw binary'
   echo '  linux.bin.ub - Create U-Boot wrapped raw binary'
-  echo '  simpleImage.<dt> - ELF image with $(arch)/boot/dts/<dt>.dts linked in'
-  echo '                   - stripped elf with fdt blob'
-  echo '  simpleImage.<dt>.unstrip - full ELF image with fdt blob'
-  echo '  *_defconfig      - Select default config from arch/microblaze/configs'
-  echo ''
+  echo '  simpleImage.<dt> - Create the following images with <dt>.dtb linked in'
+  echo '                    simpleImage.<dt>        : raw image'
+  echo '                    simpleImage.<dt>.ub     : raw image with U-Boot header'
+  echo '                    simpleImage.<dt>.unstrip: ELF (identical to vmlinux)'
+  echo '                    simpleImage.<dt>.strip  : stripped ELF'
   echo '  Targets with <dt> embed a device tree blob inside the image'
   echo '  These targets support board with firmware that does not'
   echo '  support passing a device tree directly. Replace <dt> with the'