ARM: dts: mmp3-dell-ariel: Fix the SPI devices

I've managed to get about everything wrong while digging these out of
OEM's board file.

Correct the bus numbers, the exact model of the NOR flash, polarity of
the chip selects and align the SPI frequency with the data sheet.

Tested that it works now, with a slight fix to the PXA SSP driver.

Link: https://lore.kernel.org/r/20200419171157.672999-16-lkundrak@v3.sk


Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>