nrf: nvm: assume sd is not enabled if interrupts are off

If interrupts are disabled, then calling sd_* functions will hardfault.
Instead, assume that it's safe to write if interrupts are disabled.

Signed-off-by: Sean Cross <sean@xobs.io>

ports/nrf/peripherals/nrf/nvm.c

@@ -40,6 +40,8 @@
 
 STATIC bool sd_is_enabled(void) {
     uint8_t sd_en = 0;
+    if (__get_PRIMASK())
+        return false;
     (void) sd_softdevice_is_enabled(&sd_en);
     return sd_en;
 }