ABI: sysfs-class-extcon: use uppercase X for wildcards

Uppercase letters X, Y and Z are handled as wildcards by
scripts/get_abi.pl.

We can't do that with lowercase letters, as they're used
everywhere.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2dfd3f80cea2d0501f6451f2e66000b00fda3346.1632994837.git.mchehab+huawei@kernel.org


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