matcha/tock: enable all plic interrupts

This is needed, in particular, by the spi driver.

Change-Id: Id5644adf9214f69dbe66061ad638783dcdc800e7

hal/src/plic_hal.rs

diff --git a/hal/src/plic_hal.rs b/hal/src/plic_hal.rs
index f85c56c..6541eed 100644
--- a/hal/src/plic_hal.rs
+++ b/hal/src/plic_hal.rs
@@ -46,18 +46,10 @@
 pub unsafe fn enable_all() {
     let plic: &PlicRegisters = &*PLIC_BASE;
 
-    // TODO(aappleby): Enable all relevant interrupts.
-    // USB hardware on current OT master branch seems to have
-    // interrupt bugs: running Alarms causes persistent USB
-    // CONNECTED interrupts that can't be masked from USBDEV and
-    // cause the system to hang. So enable all interrupts except
-    // for the USB ones. Some open PRs on OT fix this, we'll re-enable
-    // USB interrurupts.
-    //
-    // https://github.com/lowRISC/opentitan/issues/3388
-    plic.enable[0].set(0xFFFF_FFFE);
-    plic.enable[1].set(0xFFFF_FFFF);
-    plic.enable[2].set(0xFFFF_0000); // USB are 64-79
+    let en_iter = plic.enable.iter();
+    for en in en_iter {
+        en.set(0xFFFF_FFFF);
+    }
 
     // Set the max priority for each interrupt. This is not really used
     // at this point.