staging: pi433: Rename struct pi433_device instances to pi433.

Just as other devices use specific names for instantiation,
struct_pi433 should also have a distinct name.
Moreover, some other structs use the "dev" or "device" in their naming
conventions for members, which can be confusing.
Signed-off-by: Shahar Avidar <ikobh7@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20240405074000.3481217-3-ikobh7@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>