cris/PCI: remove pcibios_assign_resources()

There's no caller of pcibios_assign_resources() in the tree.  It is
exported, so an out-of-tree module *could* call it, but no other arch
exports pcibios_assign_resources(), so it would have to be a CRIS-specific
module.  I doubt such a caller exists.

CC: Mikael Starvik <starvik@axis.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>