Release the node reference by calling of_node_put(flash) in the probe.

Fixes: ca7d8b98 ("memory: add Renesas RPC-IF driver")
Reported-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Pavel Machek (CIP) <pavel@denx.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201126191146.8753-4-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Krzysztof Kozlowski <krzk@kernel.org>