MAINTAINERS: Update mailing list for Renesas SoC Development

Update the mailing list used for development of support for
Renesas SoCs and related drivers.

Up until now the linux-sh mailing list has been used, however,
Renesas SoCs are now much wider than the SH architecture and there
is some desire from some for the linux-sh list to refocus on
discussion of the work on the SH architecture.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Rich Felker <dalias@libc.org>
Acked-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>