arch/cris: Remove unnecessary kmalloc casts

And separate declaration from allocation
Still no error checking on failure, but it probably doesn't matter.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>