csky: Implement ptrace regs and stack API

Needed for kprobes support. Copied and adapted from Patrick's patch,
but it has been modified for csky's pt_regs.

ref:
https://lore.kernel.org/linux-riscv/[email protected]/raw

Signed-off-by: Guo Ren <[email protected]>
Cc: Patrick Staehlin <[email protected]>
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 047427f..2dfd3fb 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -48,6 +48,7 @@
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_DMA_CONTIGUOUS
+	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select MAY_HAVE_SPARSE_IRQ