linux-phytec-ti

kbuild: drop redundant "PHONY += FORCE"

"PHONY += FORCE" is already cared by scripts/Makefile.build,
which these files are included from.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Marek <mmarek@suse.com>