Look at the following forum post. Notice the caveat though, making a mistake or incorrectly applying a logo can brick the system.
Newer UEFI bios do not have Bitmap Utilities for Custom Logo that the user has access to.
Dell can make provision for this but its usually only for an OEM not an end user.
The post from 2010 does not apply to a UEFI bios with Secure Boot Certifcates.
Hardware BIOS Security measures do not allow users to modify the bios in any way.