hw/sd: sd: Fix address check in sd_erase()

For high capacity memory cards, the erase start address and end
address are multiplied by 512, but the address check is still
based on the original block number in sd->erase_{start, end}.

Fixes: 1bd6fd8e ("hw/sd/sdcard: Do not attempt to erase out of range addresses")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210216150225.27996-2-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>