ASoC: max98388: Fix missing increment of variable slot_found

ASoC: max98388: Fix missing increment of variable slot_found

The variable slot_found is being initialized to zero and inside
a for-loop is being checked if it's reached MAX_NUM_CH, however,
this is currently impossible since slot_found is never changed.
In a previous loop a similar coding pattern is used and slot_found
is being incremented. It appears the increment of slot_found is
missing from the loop, so fix the code by adding in the increment.

Fixes: 6a8e1d46f062 ("ASoC: max98388: add amplifier driver")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://patch.msgid.link/20241010182032.776280-1-colin.i.king@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>