ASoC: samsung: idma: Check of ioremap return value

Because of the potential failure of the ioremap(), the buf->area could
be NULL.
Therefore, we need to check it and return -ENOMEM in order to transfer
the error.

Fixes: f09aecd5

 ("ASoC: SAMSUNG: Add I2S0 internal dma driver")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211228034026.1659385-1-jiasheng@iscas.ac.cn


Signed-off-by: Mark Brown <broonie@kernel.org>