intel_th: Depend on HAS_IOMEM

This driver requires io memory to operate, so don't even consider it
for NO_IOMEM architectures.

Reported-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>