getting error while make in linux on ubuntu bbb

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  CC      arch/x86/kernel/acpi/apei.o
  CC      arch/x86/kernel/acpi/cstate.o
  LD      arch/x86/kernel/acpi/built-in.o
arch/x86/kernel/acpi/cstate.o: In function `of_changeset_add_property_copy':
/home/rajesh/ownbuilt/bb-kernel/KERNEL/include/linux/of.h:1092: multiple definition of `of_changeset_add_property_copy'
arch/x86/kernel/acpi/boot.o:/home/rajesh/ownbuilt/bb-kernel/KERNEL/include/linux/of.h:1092: first defined here
arch/x86/kernel/acpi/cstate.o: In function `of_changeset_add_property_string':
/home/rajesh/ownbuilt/bb-kernel/KERNEL/include/linux/of.h:1098: multiple definition of `of_changeset_add_property_string'
arch/x86/kernel/acpi/boot.o:/home/rajesh/ownbuilt/bb-kernel/KERNEL/include/linux/of.h:1098: first defined here
scripts/Makefile.build:337: recipe for target 'arch/x86/kernel/acpi/built-in.o' failed
make[3]: *** [arch/x86/kernel/acpi/built-in.o] Error 1
scripts/Makefile.build:403: recipe for target 'arch/x86/kernel/acpi' failed
make[2]: *** [arch/x86/kernel/acpi] Error 2
scripts/Makefile.build:403: recipe for target 'arch/x86/kernel' failed
make[1]: *** [arch/x86/kernel] Error 2
Makefile:947: recipe for target 'arch/x86' failed
make: *** [arch/x86] Error 2