mtd: rawnand: stm32_fmc2: remove useless inline comments

Remove inline comments that are useless since function label are
self explanatory.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1588756279-17289-3-git-send-email-christophe.kerello@st.com