staging: vc04_services: handle kzalloc failure

The kzalloc here was being used without checking the return - if the
kzalloc fails return VCHIQ_ERROR. The call-site of
vchiq_platform_init_state() vchiq_init_state() was not responding
to an allocation failure so checks for != VCHIQ_SUCCESS
and pass VCHIQ_ERROR up to vchiq_platform_init() which then
will fail with -EINVAL.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reported-by: kbuild test robot <lkp@intel.com>
Acked-By: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>