auxdisplay: img-ascii-lcd: Only build on archs that have IOMEM

[ Upstream commit 141cbfba1d0502006463aa80f57c64086226af1a ]

This avoids the MODPOST error:

  ERROR: "devm_ioremap_resource" [drivers/auxdisplay/img-ascii-lcd.ko] undefined!

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>