km/arm: set SPI NOR Flash default parameters

These parameters are used by the the sf probe command that are used by
our update script and they therefore need to be set for all of our
boards.

The timing is the same as for the ENV SPI NOR Flash (since it's the
same physical device) and takes the boco2 delay on the bus into account.

Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
cc: Holger Brunck <holger.brunck@keymile.com>
Acked-by: Prafulla Wadaskar <Prafulla@marvell.com>