x86, suspend, acpi: correct and add comments about Big Real Mode
x86, suspend, acpi: correct and add comments about Big Real Mode

Explain that we set up the descriptors for Big Real Mode, and why we
do so.  In particular, one system that is known to fail without it is
the Lenovo X61.

Signed-off-by: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs