Add SPI NOR Flash driver, WIP.

src/drivers/Spi.cpp

@@ -0,0 +1,29 @@
+#include <hal/nrf_gpio.h>
+#include "Spi.h"
+
+using namespace Pinetime::Drivers;
+
+Spi::Spi(SpiMaster& spiMaster, uint8_t pinCsn) :
+        spiMaster{spiMaster}, pinCsn{pinCsn} {
+
+}
+
+bool Spi::Write(const uint8_t *data, size_t size) {
+  return spiMaster.Write(pinCsn, data, size);
+}
+
+bool Spi::Read(uint8_t *data, size_t size) {
+  return spiMaster.Read(pinCsn, data, size);
+}
+
+void Spi::Sleep() {
+  // TODO sleep spi
+  nrf_gpio_cfg_default(pinCsn);
+}
+
+bool Spi::Init() {
+  nrf_gpio_pin_set(pinCsn); /* disable Set slave select (inactive high) */
+  return true;
+}
+
+