dmaengine: axi-dmac: add a check for devm_regmap_init_mmio

dmaengine: axi-dmac: add a check for devm_regmap_init_mmio

commit a5b982af953bcc838cd198b0434834cc1dff14ec upstream.

The driver misses checking the result of devm_regmap_init_mmio().
Add a check to fix it.

Fixes: fc15be39a827 ("dmaengine: axi-dmac: add regmap support")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20191209085711.16001-1-hslester96@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>