ASoC: soc-dapm: cleanup cppcheck warning at soc_dapm_dai_stream_event()

This patch cleanups below cppcheck warning.

sound/soc/soc-dapm.c:4368:15: style: The scope of the variable 'ep' can be reduced. [variableScope]
 unsigned int ep;
              ^

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87im0ku23z.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>