dmaengine: ti: k3-udma: Fix fall-through warning for Clang

Fix the following fallthrough warning:

drivers/dma/ti/k3-udma.c:4951:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]

Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>