sh: add support for sh7752evb board

The R0P7752C00000RZ board has SH7752, 512MB DDR3-SDRAM, SPI ROM,
Gigabit Ethernet, and eMMC.

This patch supports 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>

doc/README.sh7752evb

@@ -0,0 +1,67 @@
+========================================
+Renesas R0P7752C00000RZ board
+========================================
+
+This board specification:
+=========================
+
+The R0P7752C00000RZ(board config name:sh7752evb) has the following device:
+
+ - SH7752 (SH-4A)
+ - DDR3-SDRAM 512MB
+ - SPI ROM 8MB
+ - Gigabit Ethernet controllers
+ - eMMC 4GB
+
+
+Configuration for This board:
+=============================
+
+You can select the configuration as follows:
+
+ - make sh7752evb_config
+
+
+This board specific command:
+============================
+
+This board has the following its specific command:
+
+ - write_mac
+
+
+1. write_mac
+
+You can write MAC address to SPI ROM.
+
+ Usage 1) Write MAC address
+
+   write_mac [GETHERC ch0] [GETHERC ch1]
+
+	For example)
+	 => write_mac 74:90:50:00:33:9e 74:90:50:00:33:9f
+		*) We have to input the command as a single line
+		   (without carriage return)
+		*) We have to reset after input the command.
+
+ Usage 2) Show current data
+
+   write_mac
+
+	For example)
+		=> write_mac
+		GETHERC ch0 = 74:90:50:00:33:9e
+		GETHERC ch1 = 74:90:50:00:33:9f
+
+
+Update SPI ROM:
+============================
+
+1. Copy u-boot image to RAM area.
+2. Probe SPI device.
+   => sf probe 0
+   SF: Detected MX25L6405D with page size 64KiB, total 8 MiB
+3. Erase SPI ROM.
+   => sf erase 0 80000
+4. Write u-boot image to SPI ROM.
+   => sf write 0x48000000 0 80000