staging: netlogic: Return zero pointer after failed kmalloc

Return a ZERO_SIZE_PTR in the xlr_config_spill function if the
kmalloc returns an invalid value. This change prevents a possible
segmentation fault as the invalid pointer is fed into PTR_ALIGN macro.

Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>