mtd: fix section mismatch for doc_probe_device

doc_probe_device() is only called from docg3_probe() which is in .init.text,
so it must be in the same section to avoid a section mismatch warning.

Signed-off-by: Ryosuke Saito <[e-mail]>
Signed-off-by: Artem Bityutskiy <[e-mail]>
Signed-off-by: David Woodhouse <[e-mail]>

drivers/mtd/devices/docg3.c

···
  * if a memory allocation failed. If floor 0 is checked, a reset of the ASIC is
  * launched.
  */
-static struct mtd_info *doc_probe_device(void __iomem *base, int floor,
-					 struct device *dev)
+static struct mtd_info * __init
+doc_probe_device(void __iomem *base, int floor, struct device *dev)
 {
 	int ret, bbt_nbpages;
 	u16 chip_id, chip_id_inv;