rp/gpio: set up gpio interrupts only once

doing this setup work repeatedly, on every wait, is unnecessary. with
nothing ever disabling the interrupt it is sufficient to enable it once
during device init and never touch it again.

embassy-rp/src/multicore.rs

@@ -33,7 +33,7 @@ use core::sync::atomic::{compiler_fence, AtomicBool, Ordering};
 
 use crate::interrupt::{Interrupt, InterruptExt};
 use crate::peripherals::CORE1;
-use crate::{interrupt, pac};
+use crate::{gpio, interrupt, pac};
 
 const PAUSE_TOKEN: u32 = 0xDEADBEEF;
 const RESUME_TOKEN: u32 = !0xDEADBEEF;
@@ -68,6 +68,9 @@ fn install_stack_guard(stack_bottom: *mut usize) {
 #[inline(always)]
 fn core1_setup(stack_bottom: *mut usize) {
     install_stack_guard(stack_bottom);
+    unsafe {
+        gpio::init();
+    }
 }
 
 /// Data type for a properly aligned stack of N bytes