vgacon: inline vc_scrolldelta_helper() into vgacon_scrolldelta()

vgacon: inline vc_scrolldelta_helper() into vgacon_scrolldelta()

Since commit 74d58cd48a8f ("USB: sisusbvga: remove console support"),
vgacon_scrolldelta() is the only user of vc_scrolldelta_helper().

Inline the helper into vgacon_scrolldelta() and drop it.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>