Fix up more strange byte writes to the PCI_ROM_ADDRESS config word

It's a dword thing, and the value we write is a dword.  Doing a byte
write to it is nonsensical, and writes only the low byte, which only
contains the enable bit.  So we enable a nonsensical address (usually
zero), which causes the controller no end of problems.

Trivial fix, but nasty to find.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>