fix(serial): now using postinc instead of lea to do iteration over bytes

src/serial.s

@@ -52,7 +52,7 @@ NOTREADY@
 POUTZSTR
   pshs a,b     ; Preserve A and B
 NEXTC@
-  ldb 0,x      ; Get next char from X
+  ldb ,x+      ; Get next char from X and increment X for next time
   cmpb #$00    ; Make sure that we aren't at a terminator
   beq END@
 NOTREADY@
@@ -60,7 +60,6 @@ NOTREADY@
   bita UARTF_LSR_THRE
   beq NOTREADY@
   stb UART_THR ; Write char
-  leax 1,x     ; Iter to next char. We X++ here because leax modifies CC.Z
   bra NEXTC@   ; Iter to next char
 END@
   puls b,a     ; Restore A and B