Add SP board as copy of Nit6xlite

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: remove ethernet, PHY support

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: remove HDMI, SGTL5000 support

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: add AR1020 touch screen on I2C3

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: Add eMMC on USDHC4

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: Add PWM buzzer on PWM1 (SD3_DAT3)

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: clean up comments about I2C assignments

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: clean up GPIOs, PWM3

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: More GPIO cleanup, button assignments

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: export GPIO outputs

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: add poweroff() routine

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
sp: Update with proper peripherals