Important fix: Use bitmask everywhere now

This PAC was generated using a patched version of svd2rust with
commit hash 43be074d21132c3a76780816010df592a3603874

It includes bugfix https://github.com/rust-embedded/svd2rust/pull/549

src/spia/fifo_clr.rs

@@ -37,7 +37,7 @@ impl<'a> RXFIFO_W<'a> {
     #[doc = r"Writes raw bits to the field"]
     #[inline(always)]
     pub fn bit(self, value: bool) -> &'a mut W {
-        self.w.bits = value as u32;
+        self.w.bits = (self.w.bits & !0x01) | (value as u32 & 0x01);
         self.w
     }
 }