platform/x86: wmi-bmof: Make use of .bin_size() callback

Until now the wmi-bmof driver had to allocate the binary sysfs
attribute dynamically since its size depends on the bmof buffer
returned by the firmware.

Use the new .bin_size() callback to avoid having to do this memory
allocation.

Tested on a Asus Prime B650-Plus.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20241206215650.2977-1-W_Armin@gmx.de


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>