hw/sd/sdhci: Block Size Register bits [14:12] is lost

Block Size Register bits [14:12] is SDMA Buffer Boundary, it is missed
in register write, but it is needed in SDMA transfer. e.g. it will be
used in sdhci_sdma_transfer_multi_blocks to calculate boundary_ variables.

Missing this field will cause wrong operation for different SDMA Buffer
Boundary settings.

Fixes: d7dfca08 ("hw/sdhci: introduce standard SD host controller")
Fixes: dfba99f1 ("hw/sdhci: Fix DMA Transfer Block Size field")
Signed-off-by: Lu Gao <lu.gao@verisilicon.com>
Signed-off-by: Jianxian Wen <jianxian.wen@verisilicon.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-ID: <20220321055618.4026-1-lu.gao@verisilicon.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>