sw64: move struct pt_regs to kapi ptrace.h

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GF7A



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This struct should be invisible to user space, and we will define
new regs struct for user in uapi later.

Signed-off-by: He Sheng <hesheng@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>