6.6.84-rc1 build regression on ia64 (and possibly other architectures)

[Frank Scheiner <frank.scheiner@web.de>]

Dear Greg,

I see that the review for 6.6.84-rc1 hasn't started yet, but as it was
already available on [1], our CI has already tried to built it for ia64
in the morning. Unfortunately that failed - I assume due to the
following **missing** upstream commit:

https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8887086ef2e0047ec321103a15e7d766be3a3874

[1]: https://web.git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?h=linux-6.6.y

Build failure (see [2]):

```
[...]
  CC      drivers/video/fbdev/core/fbcon.o
drivers/video/fbdev/core/fbcon.c: In function 'fb_console_setup':
drivers/video/fbdev/core/fbcon.c:478:33: error: 'fb_center_logo' undeclared (first use in this function); did you mean 'fb_prepare_logo'?
  478 |                                 fb_center_logo = true;
      |                                 ^~~~~~~~~~~~~~
      |                                 fb_prepare_logo
drivers/video/fbdev/core/fbcon.c:478:33: note: each undeclared identifier is reported only once for each function it appears in
drivers/video/fbdev/core/fbcon.c:485:33: error: 'fb_logo_count' undeclared (first use in this function); did you mean 'file_count'?
  485 |                                 fb_logo_count = simple_strtol(options, &options, 0);
      |                                 ^~~~~~~~~~~~~
      |                                 file_count
make[8]: *** [scripts/Makefile.build:243: drivers/video/fbdev/core/fbcon.o] Error 1
[...]
```

[2]: https://github.com/linux-ia64/linux-stable-rc/actions/runs/13914712427/job/38935973485#step:8:1458

[3] (fa671e4f1556e2c18e5443f777a75ae041290068 upstream) includes
definitions for these variables, but they are guarded by CONFIG_LOGO.
But in `drivers/video/fbdev/core/fbcon.c` those variables are used
unguarded with 6.6.84-rc1. The above upstream commit (8887086) fixes
that IIUC. Not build-tested yet, though.

[3]: https://web.git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?h=linux-6.6.y&id=6562a182d204492b7c1ccdf857b05b46a9d917a0

Cheers,
Frank