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 <bmeng.cn@gmail.com>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <1613447214-81951-5-git-send-email-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>