kbuild: remove redundant LDFLAGS clearing in arch/*/Makefile
Since commit ce99d0bf312d ("kbuild: clear LDFLAGS in the top Makefile"),
the top-level Makefile caters to this.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>