Documentation: Tiny headline extension

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
driver: Round up image region mappings to page boundaries

This fixes a Linux oops when loading images of non-page-aligned size.
More precisely, ioremap_page_range becomes unhappy when we try to map
partial pages.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>