pci: ensure enumeration of all devices in pci_init

Use the uclass_first_device_check and uclass_next_device_check functions
instead of uclass_first_device and uclass_next_device in pci_init. This
ensures that all PCI devices are tried to be probed. Currently if a
device fails to probe, the enumeration stops and the devices which come
after the failed device are not probed.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Cc: Stefan Roese <sr@denx.de>
Cc: Anton Schubert <anton.schubert@gmx.de>
Cc: Dirk Eibach <dirk.eibach@gdsys.cc>
Cc: Mario Six <mario.six@gdsys.cc>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Phil Sutter <phil@nwl.cc>
Cc: VlaoMao <vlaomao@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>