hw/sd: sd: Fix CMD30 response type

Per the "Physical Layer Specification Version 8.00", table 4-26
(SD mode) and table 7-3 (SPI mode) command descriptions, CMD30
response type is R1, not R1b.

Fixes: a1bb27b1 ("SD card emulation initial implementation")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210216150225.27996-4-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>