ASoC: SOF: ipc4-pcm: Move out be_rate initialization from for loop in fixup

Instead of initializing the be_rate within the loop by checking i == 0 at
each iteration, move the be_rate reference initialization from the loop.
For BE single rate check we will have single comparison done at each
iteration compared to two in case the num_input_formats were higher than 1.

We still need to run the loop from index 0 to check for FE-BE rate match.

The patch also fixes bogus reports from gcc static analyzer thinking that
be_rate is used uninitialized later in the function (which was not true).

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://patch.msgid.link/20250206094914.21135-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>