firewire: ohci: change confusing name of a struct member

We have got

	struct descriptor *descriptors;
	dma_addr_t         descriptors_bus;

	dma_addr_t         buffer_bus;
	struct descriptor buffer[0];

	void      *misc_buffer;
	dma_addr_t misc_buffer_bus;

	__be32    *config_rom;
	dma_addr_t config_rom_bus;
	__be32    *next_config_rom;
	dma_addr_t next_config_rom_bus;

But then we have got

	__le32    *self_id_cpu;
	dma_addr_t self_id_bus;

Better apply the pattern of xyz vs. xyz_bus to self_id vs. self_id_bus
as well.  The _cpu suffix looks particularly weird in conversions from
little endian to CPU endian.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>