soc: apple: rtkit: Implement OSLog buffers properly

soc: apple: rtkit: Implement OSLog buffers properly

Apparently nobody can figure out where the old logic came from, but it
seems like it has never been actually used on any supported firmware to
this day. OSLog buffers were apparently never requested.

But starting with 13.3, we actually need this implemented properly for
MTP (and later AOP) to work, so let's actually do that.

Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://lore.kernel.org/r/20250226-apple-soc-misc-v2-2-c3ec37f9021b@svenpeter.dev
Signed-off-by: Sven Peter <sven@svenpeter.dev>