Stephen Rothwell pointed out that pcmcia can't be enabled on sparc64.

There is an empty non-prompt PCMCIA explicit entry in
arch/sparc/Kconfig but that doesn't do anything.

32-bit sparc needs a small hack to make this work, since it doesn't
use the generic IRQ layer yes.  We have to provide a dummy definition
of probe_irq_mask(), since this is used by the yenta socket driver.
Signed-off-by: David S. Miller <davem@davemloft.net>