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

In the Linux kernel, the following vulnerability has been resolved: 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.