PCI: designware-plat: Update author email address

Although I am leaving Synopsys, I would like to keep working with the linux
kernel community and help in what you might find useful.  For that I am
sending this patch to change my contact e-mail.

Signed-off-by: Joao Pinto <jpinto@synopsys.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>