CVE-2022-48723 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.