ARM: dts: at91: at91-sama5d27_som1: add QSPI1 + SPI NOR memory nodes

Configure the QSPI1 controller pin muxing and declare the
jedec,spi-nor memory (SST26VF064).

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
[tudor.ambarus@microchip.com: add spi-rx/tx-bus-width, drop partitions,
reword commit.]
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>