arm64: stacktrace: fix comment

Due to a copy-paste error, we describe struct stackframe::pc as a
snapshot of the `fp` field rather than the `lr` field.

Fix the comment.

Signed-off-by: Mark Rutland <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Madhavan T. Venkataraman <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Will Deacon <[email protected]>
Reviewed-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: mrutland-arm

arch/arm64/include/asm/stacktrace.h

@@ -35,7 +35,7 @@ struct stack_info {
  * accounting information necessary for robust unwinding.
  *
  * @fp:          The fp value in the frame record (or the real fp)
- * @pc:          The fp value in the frame record (or the real lr)
+ * @pc:          The lr value in the frame record (or the real lr)
  *
  * @stacks_done: Stacks which have been entirely unwound, for which it is no
  *               longer valid to unwind to.