aic7xxx: replace kmalloc/memset by kzalloc

This replaces kmalloc + memset by a call to kzalloc

This also fixes one checkpatch.pl issue in the process.

This improvement was suggested by "make coccicheck"

Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>