video: fbdev: aty: Fix set but not used warnings

video: fbdev: aty: Fix set but not used warnings

Fix W=1 warnings about variables assigned but never used.

- Drop variables that were set but never used
- Make variable definition conditional on ATARI

v2:
  - Fix m68k build error (kernel test robot)
  - Improve subject (Lee Jones)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reported-by: kernel test robot <lkp@intel.com> # m68k build fix
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Joe Perches <joe@perches.com>
Cc: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Cc: Jason Yan <yanaijie@huawei.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201128224114.1033617-6-sam@ravnborg.org