git-mailrc: update Masahiro's email address

I have transferred to Socionext Inc.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

doc/git-mailrc

@@ -31,7 +31,7 @@ alias luka           Luka Perkov <luka.perkov@sartura.hr>
 alias lukma          Lukasz Majewski <l.majewski@samsung.com>
 alias macpaul        Macpaul Lin <macpaul@andestech.com>
 alias marex          Marek Vasut <marex@denx.de>
-alias masahiro       Masahiro Yamada <yamada.m@jp.panasonic.com>
+alias masahiro       Masahiro Yamada <yamada.masahiro@socionext.com>
 alias monstr         Michal Simek <monstr@monstr.eu>
 alias panto          Pantelis Antoniou <panto@antoniou-consulting.com>
 alias prafulla       Prafulla Wadaskar <prafulla@marvell.com>