ASoC: pxa: Use devm_clk_get_optional() for extclk clock

ASoC: pxa: Use devm_clk_get_optional() for extclk clock

The Device Tree binding defines the extclk clock as an optional
property, but the driver currently uses devm_clk_get() and manually
handles the absence of the clock.

Use devm_clk_get_optional() to match the binding and simplify the
optional clock handling. This also propagates errors other than the
absence of the optional clock, including -EPROBE_DEFER.

This changes the existing behavior for errors other than
-EPROBE_DEFER. RFC to discuss whether these errors should cause probe
to fail rather than being treated as an unavailable optional clock.

Fixes: 90eb6b59d311 ("ASoC: pxa-ssp: add support for an external clock in devicetree")
Signed-off-by: bui duc phuc <phucduc.bui@gmail.com>
Link: https://patch.msgid.link/20260811100949.61142-1-phucduc.bui@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>