Allow implementations of the match() callback in struct bus_type to
return errors and if it's -EPROBE_DEFER then queue the device for
deferred probing.

This is useful to buses such as AMBA in which devices are registered
before their matching information can be retrieved from the HW
(typically because a clock driver hasn't probed yet).

[changed if-else code structure, adjusted documentation to match the code,
extended comments]
Signed-off-by: NTomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>