mtd: devices: docg3: Use correct function names in comment blocks

The incorrect function name is being used in the comment for functions
doc_set_reliable_mode, doc_read_seek and docg3_probe. Correct these
comments.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220805175423.2374939-1-colin.i.king@gmail.com