ram: rk3399: Add lpddr4 set rate support

ram: rk3399: Add lpddr4 set rate support

Unlike rest of dram type chips, LPDDR4 initialization start
with at board selected frequency (say 50MHz) and then it
switches into 400MHz and 800MHz simultaneously to make the
proper sequence work on each channel with associated training.

The lpddr4 set rate sequnce will follow by setting lpddr4
- dq out
- ca odt
- MR3
- MR12
- MR14
registers sets in sequential order.

Here is sameple log about LPDDR4-100 init sequence in Rockpro64:

Channel 0: LPDDR4, 50MHz
BW=32 Col=10 Bk=8 CS0 Row=15 CS1 Row=15 CS=2 Die BW=16 Size=2048MB
Channel 1: LPDDR4, 50MHz
BW=32 Col=10 Bk=8 CS0 Row=15 CS1 Row=15 CS=2 Die BW=16 Size=2048MB
256B stride
channel 0 training pass
channel 1 training pass
change freq to 400 MHz 0, 1
channel 0 training pass
channel 1 training pass
change freq to 800 MHz 1, 0

This patch add support to this init sequence via lpddr4 set rate
by taking sdram timing parameters from 400, 800 .inc files.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: YouMin Chen <cym@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
(Fix travis error, use one ret instead of ret[2] in set_ctrl)
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>