via-velocity: velocity_init_{rd/tx}_ring use kcalloc(..., GFP_KERNEL).

Allocate and free everyting outside of the locked section.

Spotted-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Fixed-by: Seguier Regis <rseguier@e-teleport.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>