The SanDisk SD8SB8U1 and likely others pads its spaces on the end rather
than the start of their serial numbers (at least when connected to a
SAS3008). This makes them difficult to wire unit numbers to with the
serial because you have to specify the trailing spaces.

We already strip leading spaces both here and when we create the devfs
names in glabel, so dev node names won't chanage because of this.

Sponsored by: Netflix