drm/bridge: analogix_dp: Use devm_drm_bridge_alloc() API

drm/bridge: analogix_dp: Use devm_drm_bridge_alloc() API

devm_drm_bridge_alloc() is the new API to be used for allocating
(and partially initializing) a private driver struct embedding
a struct drm_bridge.

Analogix DP driver somehow missed the automated conversion in commit
9c399719cfb9 ("drm: convert many bridge drivers from devm_kzalloc() to
devm_drm_bridge_alloc() API"), what causes the following warning:

------------[ cut here ]------------
WARNING: lib/refcount.c:25 at drm_bridge_attach+0x2c/0x248, CPU#1: kworker/u8:1/34
refcount_t: addition on 0; use-after-free.
Modules linked in:
CPU: 1 UID: 0 PID: 34 Comm: kworker/u8:1 Not tainted 6.16.0-rc3-next-20250627-dirty #15839 PREEMPT
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: events_unbound deferred_probe_work_func
Call trace:
 unwind_backtrace from show_stack+0x10/0x14
 show_stack from dump_stack_lvl+0x68/0x88
 dump_stack_lvl from __warn+0x94/0x1f0
 __warn from warn_slowpath_fmt+0x124/0x1bc
 warn_slowpath_fmt from drm_bridge_attach+0x2c/0x248
 drm_bridge_attach from analogix_dp_bind+0x70/0xc8
 analogix_dp_bind from exynos_dp_bind+0x58/0xc4
 exynos_dp_bind from component_bind_all+0x11c/0x27c
 component_bind_all from exynos_drm_bind+0xe8/0x198
 exynos_drm_bind from try_to_bring_up_aggregate_device+0x200/0x2d8
 try_to_bring_up_aggregate_device from __component_add+0xb0/0x170
 __component_add from exynos_dp_probe+0xc0/0x164
 exynos_dp_probe from platform_probe+0x5c/0xb8
 platform_probe from really_probe+0xe0/0x3d8
 really_probe from __driver_probe_device+0x9c/0x1e0
 __driver_probe_device from driver_probe_device+0x30/0xc0
 driver_probe_device from __device_attach_driver+0xa8/0x120
 __device_attach_driver from bus_for_each_drv+0x84/0xdc
 bus_for_each_drv from __device_attach+0xb0/0x20c
 __device_attach from bus_probe_device+0x8c/0x90
 bus_probe_device from deferred_probe_work_func+0x98/0xe0
 deferred_probe_work_func from process_one_work+0x24c/0x70c
 process_one_work from worker_thread+0x1b8/0x3bc
 worker_thread from kthread+0x13c/0x264
 kthread from ret_from_fork+0x14/0x28
...
---[ end trace 0000000000000000 ]---

Fix this by switching the driver to the new API.

Note the above warning only appears starting with commit a7748dd127ea
("drm/bridge: get/put the bridge reference in drm_bridge_add/remove()")
which is the first commmit having added a drm_bridge_get/put() pair and
thus exposing the incorrect initial refcount issue.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: a7748dd127ea ("drm/bridge: get/put the bridge reference in drm_bridge_add/remove()")
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://lore.kernel.org/r/20250627165652.580798-1-m.szyprowski@samsung.com
[Luca: add Fixes tag and mention the reason in commit message]
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>