Smatch reports below warnings [1] wrt dereferencing rm_res when it can
potentially be ERR_PTR(). This is possible when entire range is
allocated to Linux
Fix this case by making sure, there is no deference of rm_res when its
ERR_PTR().

[1]:
 drivers/dma/ti/k3-udma.c:4524 udma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
 drivers/dma/ti/k3-udma.c:4537 udma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
 drivers/dma/ti/k3-udma.c:4681 bcdma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
 drivers/dma/ti/k3-udma.c:4696 bcdma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
 drivers/dma/ti/k3-udma.c:4711 bcdma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
 drivers/dma/ti/k3-udma.c:4848 pktdma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
 drivers/dma/ti/k3-udma.c:4861 pktdma_setup_resources() error: 'rm_res' dereferencing possible ERR_PTR()
Reported-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/r/20211209180957.29036-1-vigneshr@ti.comSigned-off-by: Vinod Koul <vkoul@kernel.org>