X86: intel_ips, check for kzalloc properly

Stanse found that there are two NULL checks missing in ips_monitor. So
check their value too and bail out appropriately if the allocation
failed.

While at it, add one more kfree to the fail path. It is not necessary
now, but may be needed in the future when a new allocation is added.
And for completeness.

Also remove unneeded initialization of the variables. They are all set
right after their declaration.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>