x86/PCI: Mark PCI BIOS initialization code as such

The pci_find_bios() function is only ever called from initialization code,
therefore can be marked as such, too.  This, in turn, allows marking other
functions called only in this context as well.

The bios32_indirect variable can be marked as __initdata as it is only
referenced from __init functions now.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Ingo Molnar <mingo@kernel.org>