capsules: kv: Support 512 byte KV values

Some of the new LoRaWAN examples are writing more then 256 bytes, so
let's up the buffer size to allow larger payloads.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

boards/components/src/kv.rs

@@ -24,7 +24,7 @@ macro_rules! kv_driver_component_static {
     ($V:ty $(,)?) => {{
         let kv = kernel::static_buf!(capsules_extra::kv_driver::KVStoreDriver<'static, $V>);
         let key_buffer = kernel::static_buf!([u8; 64]);
-        let value_buffer = kernel::static_buf!([u8; 256]);
+        let value_buffer = kernel::static_buf!([u8; 512]);
 
         (kv, key_buffer, value_buffer)
     };};
@@ -52,15 +52,15 @@ impl<V: hil::kv::KVPermissions<'static>> Component for KVDriverComponent<V> {
     type StaticInput = (
         &'static mut MaybeUninit<KVStoreDriver<'static, V>>,
         &'static mut MaybeUninit<[u8; 64]>,
-        &'static mut MaybeUninit<[u8; 256]>,
+        &'static mut MaybeUninit<[u8; 512]>,
     );
     type Output = &'static KVStoreDriver<'static, V>;
 
     fn finalize(self, static_buffer: Self::StaticInput) -> Self::Output {
         let grant_cap = create_capability!(capabilities::MemoryAllocationCapability);
 
         let key_buffer = static_buffer.1.write([0; 64]);
-        let value_buffer = static_buffer.2.write([0; 256]);
+        let value_buffer = static_buffer.2.write([0; 512]);
 
         let driver = static_buffer.0.write(KVStoreDriver::new(
             self.kv,