ASoC: sti: Return errors from regmap_field_alloc()

ASoC: sti: Return errors from regmap_field_alloc()

When regmap_field_alloc() fails, it can return an error. Specifically,
it will return PTR_ERR(-ENOMEM) when the allocation returns a NULL
pointer. The code then uses these allocations with a simple NULL check:

    if (player->clk_sel) {
        // May dereference invalid pointer (-ENOMEM)
        err = regmap_field_write(player->clk_sel, ...);
    }

Ensure initialization fails by forwarding the errors from
regmap_field_alloc(), thus avoiding the use of the invalid pointers.

Fixes: 76c2145ded6b ("ASoC: sti: Add CPU DAI driver for playback")
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Link: https://patch.msgid.link/20260220152634.480766-2-sander@svanheule.net
Signed-off-by: Mark Brown <broonie@kernel.org>