Documentation: fb: Retitle driver docs

Documentation: fb: Retitle driver docs

Many framebuffer driver docs are copied from vesafb docs as their
template, including "What is <driver name>" title. Such title
implies the introductory section, however, and not the whole docs.

Retitle them.

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>