applespi: Remove the need to modify the DSDT.

Much of the information supplied in the DSDT resource-template returned
when the DSDT is modified is also available from the _DSM method. So we
register ourselves as an ACPI driver for the device, and then create and
register the spi device ourselves, configuring it from the information
returned by the _DSM method.

README.md

@@ -2,7 +2,7 @@ Very simple, work in progress input driver for the SPI keyboard / trackpad found
 
 Using it:
 ---------
-To get this driver to work on a 2016 12" MacBook, you'll need to boot the kernel with `intremap=nosid`. Also, you'll need to modify your DSDT as described by Leif Liddy at https://bugzilla.kernel.org/attachment.cgi?id=206671. (but don't worry about applying patches. Also see https://wiki.archlinux.org/index.php/DSDT for a quicker way to load custom DSDTs without recompiling)
+To get this driver to work on a 2016 12" MacBook, you'll need to boot the kernel with `intremap=nosid`.
 
 This should result in the intel-lpss driver attaching itself to the SPI controller, and exposing the `APP000D` device.
 
@@ -26,7 +26,6 @@ What doesn't work:
 Known bugs:
 -----------
 * Occasionally, the SPI device can get itself into a state where it causes an interrupt storm. There should be a way of resetting it, or better yet avoiding this state altogether.
-* You shouldn't have to modify your DSDT to get it running.
 
 Interrupts:
 -----------