staging: fbtft: Fix build failure when CONFIG_FB_DEVICE=n

staging: fbtft: Fix build failure when CONFIG_FB_DEVICE=n

When CONFIG_FB_DEVICE is disabled, struct fb_info does
not provide a valid dev pointer. Direct dereferences of
fb_info->dev therefore result in build failures.

Fix this by avoiding direct accesses to fb_info->dev and
switching the affected debug logging to framebuffer helpers
that do not rely on a device pointer.

This fixes the following build failure reported by the
kernel test robot.

Fixes: a06d03f9f238 ("staging: fbtft: Make FB_DEVICE dependency optional")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202601110740.Y9XK5HtN-lkp@intel.com
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Chintan Patel <chintanlike@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>