MAINTAINERS: Add Bin Meng as co-maintainer for SD/MMC cards

There is new interest in the SD/MMC device emulation, so it
would be good to have more than only one maintainer / reviewer
for it.

Bin Meng proved by his contributions a deep understanding of the
SD cards internals, so let's add him to the corresponding section
in the MAINTAINERS file.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20210216132841.1121653-1-f4bug@amsat.org>

MAINTAINERS

@@ -1754,6 +1754,7 @@ F: hw/ssi/xilinx_*
 
 SD (Secure Card)
 M: Philippe Mathieu-Daudé <f4bug@amsat.org>
+M: Bin Meng <bin.meng@windriver.com>
 L: qemu-block@nongnu.org
 S: Odd Fixes
 F: include/hw/sd/sd*