mtd: rawnand: meson: read/write access for boot ROM pages

Boot ROM on Meson needs some pages to be read/written in a special mode:
384 byte ECC mode (so called "short" by Amlogic) and with scrambling
enabled. Such pages are located on the chip in the following way (for
example):

[ p0 ][ p1 ][ p2 ][ p3 ][ p4 ][ p5 ][ p6 ][ p7 ] ... [ pN ]
  ^           ^           ^           ^

pX is page number "X". "^" means "special" page used by boot ROM - e.g.
every 2nd page in the range of [0, 7]. Step (2 here) and last page in
range is read from the device tree.

Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
Link: https://lore.kernel.org/r/20240826131710.29746-4-avkrasnov@salutedevices.com


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>