drm/arm/komeda: Fix komeda probe failing if there are no links in the secondary pipeline

Since commit 4cfe5cc0 ("drm/arm/komeda: Remove component framework and
add a simple encoder"), the devm_drm_of_get_bridge() call happens
regardless of whether any remote nodes are available on the pipeline. Fix
this by moving the bridge attach to its own function and calling it
conditional on there being an output link.

Fixes: 4cfe5cc0

 ("drm/arm/komeda: Remove component framework and add a simple encoder")
Signed-off-by: Faiz Abbas <faiz.abbas@arm.com>
[Corrected Commit-id of the fixed patch to match mainline]
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219100915.192475-2-faiz.abbas@arm.com