sw64: add basic livepatch support on SW64

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I645PM



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This patch adds livepatch support on SW64. It requires support from
DYNAMIC_FTRACE_WITH_REGS option. Livepatch is handled by a special
ftrace handler ftrace_regs_caller(). The livepatch handler modifies
the regs->r28 so as to make ftrace_regs_caller() return to the new
patched function.

Signed-off-by: Gu Zitao <guzitao@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>