for compatible 32bit and 64bit, we use 0x82xxxxxx as function ID,
we modify SIP call function return value to 32 bit.

Change-Id: Ib99b03a9ea423853aaa296dcc634ee82c622a552

add dram driver, and kernel can through sip function talk to bl31 to
do ddr frequency scaling. and ddr auto powerdown.

Change-Id: I0d0f2869aed95e336c6e23ba96a9310985c84840

Software executing in the normal world and in the trusted world at
exception levels lower than EL3 will request runtime services using the
SMC instruction.

See the documentation here:
https://github.com/ARM-software/arm-trusted-firmware/blob/master/docs/
rt-svc-writers-guide.md

This to be implemented as an EL3 Runtime Service in rockchip BL31
platform port, using the "SiP Service Call" range as specified in the
SMC Calling Convention.
This doesn't support any SMC yet, we will support it in later.

Change-Id: I0a638dd0b653c28b08f79d89f77ed7c69864017d