Pull Kbuild fixes from Masahiro Yamada:
- fix missed rebuild of DT schema check
- add some phony targets to PHONY
- fix comments and documents
* tag 'kbuild-fixes-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: get rid of trailing slash from subdir- example
kbuild: add dt_binding_check to PHONY in a correct place
kbuild: add dtbs_check to PHONY
kbuild: remove unneeded semicolon at the end of cmd_dtb_check
kbuild: fix DT binding schema rule to detect command line changes
kbuild: remove wrong documentation about mandatory-y
kbuild: add comment for V=2 mode