advansys fix on ISA-less configs

The code

        if (shost->dma_channel != NO_ISA_DMA)
                free_dma(shost->dma_channel);

in there is triggerable only if we have CONFIG_ISA (we only set ->dma_channel to
something other than NO_ISA_DMA under #ifdef CONFIG_ISA).  OTOH, free_dma() is
not guaranteed to be there in absense of CONFIG_ISA.  IOW, driver runs into
undefined symbols on PCI-but-not-ISA configs (e.g. on frv) and it's a false
positive.

Fix: put the entire if () under #ifdef CONFIG_ISA; behaviour doesn't change and
dependency on free_dma() disappears for !CONFIG_ISA.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>