fbcon: don't inline updatescrollmode

Updatescrollmode is marked inline, but it's big and is called only from
non-critical codepaths (fbcon_resize, fbcon_switch, fbcon_modechanged).
Dropping it saves almost 800 bytes of text size.

   text    data     bss     dec     hex filename
  23859     287    8448   32594    7f52 drivers/video/console/fbcon.o.before
  23065     287    8448   31800    7c38 drivers/video/console/fbcon.o.after

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>