PCI: mobiveil: Fix the Class Code field

Fix up the Class Code field in PCI configuration space and set it to
PCI_CLASS_BRIDGE_PCI.

Move the Class Code fixup to function mobiveil_host_init() where
it belongs.

Fixes: 9af6bcb1 ("PCI: mobiveil: Add Mobiveil PCIe Host Bridge IP driver")
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Minghuan Lian <Minghuan.Lian@nxp.com>
Reviewed-by: Subrahmanya Lingappa <l.subrahmanya@mobiveil.co.in>