thermal: max77620: fix pinmux conflict on reprobe

Use the new helper for reusing a device-tree node of another device
instead of managing the node references explicitly.

This also makes sure that the new of_node_reuse flag is set if the
device is ever reprobed, something which specifically now avoids driver
core from attempting to claim any pinmux resources already claimed by
the parent device.

Fixes: ec4664b3 ("thermal: max77620: Add thermal driver for reporting junction temp")
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>