dmaengine: sf-pdma: Simplify the error handling path in 'sf_pdma_probe()'

There is no need to explicitly free memory that have been 'devm_kzalloc'ed.
Simplify the probe function accordingly.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Tested-by: Green Wan <green.wan@sifive.com>
Reviewed-by: Green Wan <green.wan@sifive.com>
Link: https://lore.kernel.org/r/20200501100824.126534-1-christophe.jaillet@wanadoo.fr


Signed-off-by: Vinod Koul <vkoul@kernel.org>