arm: socfpga: Add DT support for SoCFPGA and add socfpga_socrates target

This patch includes the latest DT sources for socfpga from the current Linux kernel. And enables CONFIG_OF_CONTROL for the new build target "socfpga_socrates" (the EBV SoCrates board) to make use of this new DT support.

Until this patch, the only SoCFPGA U-Boot target in mainline is "socfpga_cyclone5". This build target is not (yet) changed to support DT. So nothing changes for this target. Even though the long-term goal should be to move all SoCFPGA targets over to DT.

One of the reasons to enable DT support in SoCFPGA is, that I need to support multiple different SPI controllers for this platform. This is the QSPI Cadence controller and the Designware SPI master controller. Both are implemented in the SoCFPGA. And enabling both controllers is only possible by using the new driver model (DM). The DM SPI code only supports DT based probing. So it was easier to move SoCFPGA to DT than to add the (deprecated) platform-data based probing to the DM SPI suport.

Note that the image with the dtb embedded is u-boot-dtb.img. This needs to be used now for those DT enabled boards instead of u-boot.img.

---
v2:
- As mentioned in the commit text, this new version does not move the default target to DT (yet). It adds support for the SoCrates board now based on this DT support as the first example. Nothing changes for the current socfpga_cyclone5 target.

 arch/arm/dts/Makefile                      |   2 +
 arch/arm/dts/socfpga.dtsi                  | 755 +++++++++++++++++++++++++++++
 arch/arm/dts/socfpga_cyclone5.dtsi         |  51 ++
 arch/arm/dts/socfpga_cyclone5_socrates.dts |  50 ++
 configs/socfpga_socrates_defconfig         |   5 +
 include/dt-bindings/reset/altr,rst-mgr.h   |  90 ++++
 6 files changed, 953 insertions(+)
 create mode 100644 arch/arm/dts/socfpga.dtsi
 create mode 100644 arch/arm/dts/socfpga_cyclone5.dtsi
 create mode 100644 arch/arm/dts/socfpga_cyclone5_socrates.dts
 create mode 100644 configs/socfpga_socrates_defconfig
 create mode 100644 include/dt-bindings/reset/altr,rst-mgr.h

index 52f8926..b946abe 100644
@@ -40,6 +40,8 @@ dtb-$(CONFIG_ZYNQ) += zynq-zc702.dtb \
 	zynq-zc770-xm013.dtb
 dtb-$(CONFIG_AM33XX) += am335x-boneblack.dtb
 
+dtb-$(CONFIG_SOCFPGA) += socfpga_cyclone5_socrates.dtb
+
 targets += $(dtb-y)
 
 DTC_FLAGS += -R 4 -p 0x1000

new file mode 100644
index 0000000..0f3896d
@@ -0,0 +1,5 @@
+CONFIG_SPL=y
++S:CONFIG_ARM=y
++S:CONFIG_TARGET_SOCFPGA_CYCLONE5=y
+CONFIG_OF_CONTROL=y
+CONFIG_DEFAULT_DEVICE_TREE="socfpga_cyclone5_socrates"

2.1.3