PCI: Fix error in panic message

Use kzalloc() instead of kmalloc() in the panic message.

[bhelgaas: drop similar ibmphp_pci.c change since it's not obviously
correct]
Link: https://lore.kernel.org/r/1594279708-34369-1-git-send-email-wang.yi59@zte.com.cn


Signed-off-by: Liao Pingfang <liao.pingfang@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>