drivers: flash: add Nordic JEDEC QSPI NOR flash driver

Most JEDEC NOR flash devices uses not only typical SPI mode
(MISO,MOSI,SCK and CS), but also QSPI mode (IO0,IO1,IO2,IO3,SCK and CS).
QSPI mode uses more data lines and as a result provide higher
throughput. If this were not enough, Nordic chips provide
hardware acceleration for read/write/erase functions, what
gives significant performance boost.
It does a lot of things "behind the scene", i.e when user has written
some data to the flash and would like to read them back, it has to wait
until the flash is ready by reading WIP bit in Status Register.
This driver does it automatically.

Signed-off-by: Kamil Lazowski <Kamil.Lazowski@nordicsemi.no>