hw/sd: sdhci: Simplify updating s->prnsts in sdhci_sdma_transfer_multi_blocks()

hw/sd: sdhci: Simplify updating s->prnsts in sdhci_sdma_transfer_multi_blocks()

s->prnsts is updated in both branches of the if () else () statement.
Move the common bits outside so that it is cleaner.

Signed-off-by: Bin Meng <[email protected]>
Tested-by: Alexander Bulekov <[email protected]>
Reviewed-by: Alexander Bulekov <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <1613447214[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>