pci: Make pci apis usable before relocation

Introduce a gd->hose to save the pci hose in the early phase so that
apis in drivers/pci/pci.c can be used before relocation. Architecture
codes need assign a valid gd->hose in the early phase.

Some variables are declared as static so change them to be either
stack variable or global data member so that they can be used before
relocation, except the 'indent' used by CONFIG_PCI_SCAN_SHOW which
just affects some print format.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>