spi: uniphier: fix reference count leak in uniphier_spi_probe()

spi: uniphier: fix reference count leak in uniphier_spi_probe()

The issue happens in several error paths in uniphier_spi_probe().
When either dma_get_slave_caps() or devm_spi_register_master() returns
an error code, the function forgets to decrease the refcount of both
`dma_rx` and `dma_tx` objects, which may lead to refcount leaks.

Fix it by decrementing the reference count of specific objects in
those error paths.

Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Reviewed-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Fixes: ad7f7899a9e8 ("spi: uniphier: Add DMA transfer mode support")
Link: https://lore.kernel.org/r/20220125101214.35677-1-xiongx18@fudan.edu.cn
Signed-off-by: Mark Brown <broonie@kernel.org>