dma/idxd: fix truncated error code in status check

dma/idxd: fix truncated error code in status check

When checking if the DMA device is active, the result of the operand will
always be zero since the err_code is truncated to 8 bits which makes
checking the 31st bit impossible.

This is fixed by changing the type of err_code to uint32_t so that it is
not truncated.

Coverity issue: 373657
Fixes: 9449330a8458 ("dma/idxd: create dmadev instances on PCI probe")

Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Conor Walsh <conor.walsh@intel.com>