pci: don't reassign to ROM res if it is not going to be enabled

A ROM resource that doesn't fit should not cause us to try to re-assign
all the bus resources.  Nobody generally cares, and re-assigning is
going to just cause way more troubles than it tries to solve.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>