Remove PC and SP write functions (at least SP write is unsound with inline asm).

Author: cr1901

src/register/pc.rs

@@ -11,9 +11,3 @@ pub fn read() -> u16 {
     }
     r
 }
-
-/// Writes `bits` to the CPU register
-#[inline(always)]
-pub unsafe fn write(bits: u16) {
-    asm!("mov {0}, R0", in(reg) bits);
-}

src/register/sp.rs

@@ -11,9 +11,3 @@ pub fn read() -> u16 {
     }
     r
 }
-
-/// Writes `bits` to the CPU register
-#[inline(always)]
-pub unsafe fn write(bits: u16) {
-    asm!("mov {0}, R1", in(reg) bits);
-}