fbcon: Avoid 'cap' set but not used warning

Fix this kernel test robot warning:

  drivers/video/fbdev/core/fbcon.c: In function 'fbcon_init':
  drivers/video/fbdev/core/fbcon.c:1028:6: warning: variable 'cap' set but not used [-Wunused-but-set-variable]

The cap variable is only used when CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
is enabled. Drop the temporary variable and use info->flags instead.

Fixes: 87ab9f6b

 ("Revert "fbcon: Disable accelerated scrolling")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/YgFB4xqI+As196FR@p100