Fix kconfig dependency warning for PC8736x_GPIO by restricting it to
X86_32.

  warning: (SCx200_GPIO && SCx200 || PC8736x_GPIO && X86) selects NSC_GPIO which has unmet direct dependencies (X86_32)

NSC_GPIO is X86_32 only.  The other driver (SCx200_GPIO) that selects
NSC_GPIO is X86_32 only (indirectly, since SCx200 depends on X86_32), so
limit this driver also.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>