LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_REGS support

This patch implements CONFIG_DYNAMIC_FTRACE_WITH_REGS on LoongArch,
which allows a traced function's arguments (and some other registers)
to be captured into a struct pt_regs, allowing these to be inspected
and modified.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>