m68k/Atari: remove the dead ATARI_SCC{,_DMA} options

It seems the driver was removed back in kernel 2.3 but the options were
forgotten.

Reported-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>