ASoC: dapm: Fix widget lookup with prefixed names across DAPM contexts

Currently dapm_find_widget() manually constructs a prefixed widget name
based on the provided DAPM context and compares it using strcmp(). This
happens to work in most cases because callers usually know which DAPM
context the target widget belongs to and pass in the matching DAPM
context.

However, this assumption breaks when search_other_contexts is enabled.
In such cases, callers may intentionally pass a different DAPM context,
while searching for a widget that actually belongs to another DAPM
context.

For example, when searching for a "DAC" widget, the widget belongs to
the codec DAPM and be registered with a codec prefix, while the caller
passes card->dapm and intends to search across all DAPM contexts. The
current implementation incorrectly applies the caller card DAPM causing
the lookup to fail even though the widget exists on the card.

Improve the matching strategy to support both use cases:
1. When the caller provides a fully qualified name with prefix, perform
   exact string matching. This preserves the ability to use prefixes for
   disambiguation.
2. When the caller provides a bare widget name without prefix, try exact
   matching first, then fall back to prefix-stripped comparison using
   snd_soc_dapm_widget_name_cmp().

To determine whether the pin name includes a prefix, a new helper
function snd_soc_dapm_pin_has_prefix() is introduced. It checks if the
pin name starts with any known component prefix on the card.

This fixes widget lookup failures when searching across different DAPM
contexts while maintaining backward compatibility for explicitly
prefixed lookups.

Fixes: ae4fc532244b ("ASoC: dapm: use component prefix when checking widget names")
Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
Assisted-by: Cody:Claude-4.5-Sonnet
Link: https://patch.msgid.link/20260507013654.2945915-2-chancel.liu@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>

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