driver-core: remove struct bus_type.drv_attrs

Now that all in-kernel users of bus_type.drv_attrs have been converted
to use drv_groups instead, the drv_attrs field, and logic surrounding
it, can be removed.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/base/bus.c
Simple merge

diff --cc include/linux/device.h
Simple merge