dpaa2-switch: Fix device reference count leak in MAC endpoint handling

dpaa2-switch: Fix device reference count leak in MAC endpoint handling

The fsl_mc_get_endpoint() function uses device_find_child() for
localization, which implicitly calls get_device() to increment the
device's reference count before returning the pointer. However, the
caller dpaa2_switch_port_connect_mac() fails to properly release this
reference in multiple scenarios. We should call put_device() to
decrement reference count properly.

As comment of device_find_child() says, 'NOTE: you will need to drop
the reference with put_device() after use'.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 84cba72956fd ("dpaa2-switch: integrate the MAC endpoint support")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250717022309.3339976-3-make24@iscas.ac.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>