Use upstream of_get_mtd_device_by_node() which should behave pretty much
the same. Implementation differences:
get_mtd_device_by_node() of_get_mtd_device_by_node()
---- ----
np->dev.of_node mtd_get_of_node(np)
-EPROBE_DEFER -ENODEV
Cc: Bernhard Frauendienst <openwrt@nospam.obeliks.de>
Cc: Bernhard Frauendienst <kernel@nospam.obeliks.de>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>