ABI: sysfs-bus-soundwire-slave: use wildcards on What definitions

An "N" upper letter is not a wildcard, nor can easily be identified
by script, specially since the USB sysfs define things like.
bNumInterfaces. Use, instead, <N>, in order to let script/get_abi.pl
to convert it into a Regex.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/416f4a746c116147abb08fb0155a6a4ed065dfd7.1631782432.git.mchehab+huawei@kernel.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>