arm64: stacktrace: delete PCS comment

The comment at the top of stacktrace.c isn't all that helpful, as it's
not associated with the code which inspects the frame record, and the
code example isn't representative of common code generation today.

Delete it.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: mrutland-arm

arch/arm64/kernel/stacktrace.c

@@ -18,21 +18,6 @@
 #include <asm/stack_pointer.h>
 #include <asm/stacktrace.h>
 
-/*
- * AArch64 PCS assigns the frame pointer to x29.
- *
- * A simple function prologue looks like this:
- * 	sub	sp, sp, #0x10
- *   	stp	x29, x30, [sp]
- *	mov	x29, sp
- *
- * A simple function epilogue looks like this:
- *	mov	sp, x29
- *	ldp	x29, x30, [sp]
- *	add	sp, sp, #0x10
- */
-
-
 static notrace void start_backtrace(struct stackframe *frame, unsigned long fp,
 				    unsigned long pc)
 {