riscv: stacktrace: Disable KASAN checks for non-current tasks

In the Linux kernel, the following vulnerability has been resolved: riscv: stacktrace: Disable KASAN checks for non-current tasks Unwinding the stack of a task other than current, KASAN would report "BUG: KASAN: out-of-bounds in walk_stackframe+0x41c/0x460" There is a same issue on x86 and has been resolved by the commit 84936118bdf3 ("x86/unwind: Disable KASAN checks for non-current tasks") The solution could be applied to RISC-V too. This patch also can solve the issue: https://seclists.org/oss-sec/2025/q4/23 [pjw@kernel.org: clean up checkpatch issues]