PCI: Add HXT vendor ID

Add the HXT vendor ID to pci_ids.h.

Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com>
[bhelgaas: split to separate patch]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
CC: Joey Zheng <yu.zheng@hxt-semitech.com>