Add an nRF RNG driver

Resolves #187

Like the stm32 driver, this has both a non-blocking and blocking API, and implements `rand_core::RngCore` for the blocking API.

embassy-nrf/src/chips/nrf52805.rs

@@ -8,6 +8,9 @@ embassy_extras::peripherals! {
     RTC0,
     RTC1,
 
+    // RNG
+    RNG,
+
     // UARTE
     UARTE0,
 

embassy-nrf/src/chips/nrf52810.rs

@@ -8,6 +8,9 @@ embassy_extras::peripherals! {
     RTC0,
     RTC1,
 
+    // RNG
+    RNG,
+
     // UARTE
     UARTE0,
 

embassy-nrf/src/chips/nrf52811.rs

@@ -8,6 +8,9 @@ embassy_extras::peripherals! {
     RTC0,
     RTC1,
 
+    // RNG
+    RNG,
+
     // UARTE
     UARTE0,
 

embassy-nrf/src/chips/nrf52820.rs

@@ -8,6 +8,9 @@ embassy_extras::peripherals! {
     RTC0,
     RTC1,
 
+    // RNG
+    RNG,
+
     // UARTE
     UARTE0,
 

embassy-nrf/src/chips/nrf52832.rs

@@ -9,6 +9,9 @@ embassy_extras::peripherals! {
     RTC1,
     RTC2,
 
+    // RNG
+    RNG,
+
     // UARTE
     UARTE0,
 

embassy-nrf/src/chips/nrf52833.rs

@@ -9,6 +9,9 @@ embassy_extras::peripherals! {
     RTC1,
     RTC2,
 
+    // RNG
+    RNG,
+
     // UARTE
     UARTE0,
     UARTE1,

embassy-nrf/src/chips/nrf52840.rs

@@ -9,6 +9,9 @@ embassy_extras::peripherals! {
     RTC1,
     RTC2,
 
+    // RNG
+    RNG,
+
     // QSPI
     QSPI,