commit 157f38f9 upstream.

Fix parent-device reference leak due to SPI-core taking an unnecessary
reference to the parent when allocating the master structure, a
reference that was never released.

Note that driver core takes its own reference to the parent when the
master device is registered.

Fixes: 49dce689 ("spi doesn't need class_device")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>