flash/nor: Add Renesas RPC HF driver

flash/nor: Add Renesas RPC HF driver

Add driver for the RPC block in HF mode on Renesas R-Car Gen3 SoCs.
This driver allows operating the on-SIP HF memory.

Note that HF is CFI compliant flash, but it is not memory mapped,
hence the need to replace all the memory accessors and read/write
functions. The write function is entirely replaced to increase
performance and is Spansion/AMD specific, since there is no known
SIP with other HF from another vendor.

Add the following two lines to board TCL file to bind the driver on
R-Car Gen3 SoC using HyperFlash:

  set _FLASHNAME $_CHIPNAME.flash
  flash bank $_FLASHNAME rpchf 0x08000000 0x4000000 2 2 $_CHIPNAME.a57.0

Change-Id: Ie18729d017eeb46e1363333ffe002d010dfc5ead
Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Reviewed-on: http://openocd.zylin.com/5149
Tested-by: jenkins
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>