efi: export sysfb_primary_display for EDID

efi: export sysfb_primary_display for EDID

The sysfb_primary_display structure is now part of efi-init.c but
conditionally defined. One of the users is missing in the condition:

aarch64-linux-ld: drivers/video/fbdev/core/fbmon.o: in function `fb_firmware_edid':
fbmon.c:(.text.fb_firmware_edid+0x3c): undefined reference to `sysfb_primary_display'

Export it whenever CONFIG_FIRMWARE_EDID is set, so the fbdev core
code can use it.

Fixes: 4fcae6358871 ("sysfb: Move edid_info into sysfb_primary_display")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202602111543.Do4nkY5l-lkp@intel.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>