MAINTAINER, git-mailrc: Update the mmc maintainer

Update to me as co-maintainer with Peng.
Additionally, update the mmc alias in git-mailrc.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Peng Fan <peng.fan@nxp.com>
diff --git a/doc/git-mailrc b/doc/git-mailrc
index 34f936f..dc7b39b 100644
--- a/doc/git-mailrc
+++ b/doc/git-mailrc
@@ -119,7 +119,7 @@
 alias fdt            uboot, sjg
 alias i2c            uboot, hs
 alias kconfig        uboot, masahiro
-alias mmc            uboot, freenix
+alias mmc            uboot, freenix, jaehoon
 alias nand           uboot
 alias net            uboot, jhersh
 alias phy            uboot, jhersh