powerpc: smp: remove hack to obtain offset of task_struct::cpu

mainline inclusion
from mainline-v5.16-rc1
commit 336868af
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4Q94A


CVE: NA

------------------------------

Instead of relying on awful hacks to obtain the offset of the cpu field
in struct task_struct, move it back into struct thread_info, which does
not create the same level of circular dependency hell when trying to
include the header file that defines it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Guan Jing <guanjing6@huawei.com>

Conflicts:
	arch/powerpc/Makefile
Reviewed-by: Chen Hui <judy.chenhui@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>