arm: mvebu: update RTC values for PCIe memory wrappers

Update the RTC (Read Timing Control) values for PCIe memory wrappers
following an ERRATA (ERRATA# TDB). This means the PCIe accesses will
used slower memory Read Timing, to allow more efficient energy
consumption, in order to lower the minimum VDD of the memory.  Will lead
to more robust memory when voltage drop occurs (VDDSEG)

The code is based on changes from Marvell's U-Boot, specifically:

https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/commit/20cd2704072512de176e048970f2883db901674b
https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/commit/eb608a7c8dd0d42b87601a61b9c0cc5615ab94b2
https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/commit/c4af19ae2bf08cf6e450e741ce4f04d402a5cb6b



Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>