block/partitions/msdos: Fix typo inidicator -> indicator

Just a fix for a small typo in msdos_partition().

Signed-off-by: Thomas Bracht Laumann Jespersen <t@laumann.xyz>
Link: https://lore.kernel.org/r/20210619195130.19348-1-t@laumann.xyz
Signed-off-by: Jens Axboe <axboe@kernel.dk>