This will be used (later) to store the list of all enabled display devices.
Add a global variable gpmdev (should really be stored in DISPLAYINFO structure)
Replace global variable gppdevPrimary by pmdev->ppdevGlobal.
- Change INIT_FUNCTION and INIT_SECTION to CODE_SEG("INIT") and DATA_SEG("INIT") respectively
- Remove INIT_FUNCTION from function prototypes
- Remove alloc_text pragma calls as they are not needed anymore