Documentation: hid-alps: Fix packet format section headings

Documentation: hid-alps: Fix packet format section headings

In "Packet Format" section, only "StickPointer data byte" subsection
heading is shown as such in htmldocs output; "Touchpad data byte" one
is in normal paragraph on the other hand.

Properly format the headings to be consistent.

Fixes: 2562756dde55 ("HID: add Alps I2C HID Touchpad-Stick support")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.com>