sh: add support for sh7753evb board

The SH7753 EVB board has SH7753, 512MB DDR3-SDRAM, SPI ROM,
Gigabit Ethernet, and eMMC.

This patch support the following functions:
 - 512MB DDR3-SDRAM, SCIF4, SPI ROM, Gigabit Ethernet, eMMC

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
net: sh-eth: add support for SH7753

SH7753 has two fast ethernet controllers and two gigabit ethernet
controllers. It is similar to SH7757.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
serial_sh: add support for SH7753

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>