platform/x86: thinkpad_acpi: Support for system debug info hotkey

New Lenovo platforms are adding the FN+N key to generate system debug
details that support can use for collecting important details on any
customer cases for Windows.
Add the infrastructure so we can do the same on Linux by sending
a KEY_VENDOR keycode to userspace.

Signed-off-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Signed-off-by: Nitin Joshi <njoshi1@lenovo.com>
Link: https://lore.kernel.org/r/20240417173124.9953-3-mpearson-lenovo@squebb.ca


[hdegoede@redhat.com: Adjust for switch to sparse-keymap keymaps]
Tested-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240424122834.19801-24-hdegoede@redhat.com