ABI: sysfs-class-bdi: use What: to describe each property

Instead of listing all bdi entries inside the description, add
one entry for each, just like the remaining ABI files.

That allows get_abi.pl script to properly parse it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/77e5904dfd275ed2670cd13779e5ef1da96e355c.1632750608.git.mchehab+huawei@kernel.org


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