iommu/fsl: Add void declarations in zero-arg functions.

Added explicit void declarations to zero-argument function headers.
The following coccinelle script was used:
@addvoid@
identifier f;
@@

f(
+ void
 ) { ... }

Signed-off-by: Chi Pham <fempsci@gmail.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>