kbuild: remove redundant LDFLAGS clearing in arch/*/Makefile

Since commit ce99d0bf31 ("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>

arch/openrisc/Makefile

@@ -19,7 +19,6 @@
 
 KBUILD_DEFCONFIG := or1ksim_defconfig
 
-LDFLAGS         :=
 OBJCOPYFLAGS    := -O binary -R .note -R .comment -S
 LDFLAGS_vmlinux :=
 LIBGCC 		:= $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)