net: ks8851: Replace malloc()+memset() with calloc()

Replace combination of malloc()+memset() with calloc() as the behavior
is exactly the same and the amount of code is reduced. Moreover, remove
printf() in the fail path, as it is useless, and return proper -ENOMEM
return code.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Eugen Hristev <eugen.hristev@microchip.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>