Configure the number of pages in the board

This permits to have portable apps.

patches/tock/01-persistent-storage.patch

@@ -349,7 +349,7 @@ index 348c746a5..5465c95f4 100644
      }
  }
 diff --git a/kernel/src/process.rs b/kernel/src/process.rs
-index c52754be3..ae6a58341 100644
+index c52754be3..26a7c47d3 100644
 --- a/kernel/src/process.rs
 +++ b/kernel/src/process.rs
 @@ -359,6 +359,15 @@ pub trait ProcessType {
@@ -415,7 +415,7 @@ index c52754be3..ae6a58341 100644
 +                .mpu()
 +                .allocate_region(
 +                    storage_location.address as *const u8,
-+                    storage_location.size,
++                    storage_location.unallocated_size,
 +                    storage_location.size,
 +                    mpu::Permissions::ReadOnly,
 +                    &mut mpu_config,
@@ -439,10 +439,10 @@ index c52754be3..ae6a58341 100644
          // memory space just for kernel and grant state. We need to make
          // sure we allocate enough memory just for that.
 diff --git a/kernel/src/sched.rs b/kernel/src/sched.rs
-index 10626a2e1..8844bc6c3 100644
+index 10626a2e1..61401b04a 100644
 --- a/kernel/src/sched.rs
 +++ b/kernel/src/sched.rs
-@@ -118,6 +118,12 @@ pub enum SchedulingDecision {
+@@ -118,6 +118,13 @@ pub enum SchedulingDecision {
      TrySleep,
  }
  
@@ -450,12 +450,13 @@ index 10626a2e1..8844bc6c3 100644
 +pub struct StorageLocation {
 +    pub address: usize,
 +    pub size: usize,
++    pub unallocated_size: usize,
 +}
 +
  /// Main object for the kernel. Each board will need to create one.
  pub struct Kernel {
      /// How many "to-do" items exist at any given time. These include
-@@ -127,6 +133,9 @@ pub struct Kernel {
+@@ -127,6 +134,9 @@ pub struct Kernel {
      /// This holds a pointer to the static array of Process pointers.
      processes: &'static [Option<&'static dyn process::ProcessType>],
  
@@ -465,7 +466,7 @@ index 10626a2e1..8844bc6c3 100644
      /// A counter which keeps track of how many process identifiers have been
      /// created. This is used to create new unique identifiers for processes.
      process_identifier_max: Cell<usize>,
-@@ -170,9 +179,17 @@ pub enum StoppedExecutingReason {
+@@ -170,9 +180,17 @@ pub enum StoppedExecutingReason {
  
  impl Kernel {
      pub fn new(processes: &'static [Option<&'static dyn process::ProcessType>]) -> Kernel {
@@ -483,7 +484,7 @@ index 10626a2e1..8844bc6c3 100644
              process_identifier_max: Cell::new(0),
              grant_counter: Cell::new(0),
              grants_finalized: Cell::new(false),
-@@ -900,4 +917,8 @@ impl Kernel {
+@@ -900,4 +918,8 @@ impl Kernel {
  
          (return_reason, time_executed_us)
      }