nit6xlite: : Update SPI NOR to match updates in main-line

    Default chip-select is done in a call-back, doesn't need
    SPI pad control.

    See commits 155fa9af9 and 3b31605ae.

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
nit6xlite: fix disable_giga environment variable

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>