Remove Zero Page linker patch RPN_PCEZP

This patch isn't used because it's meant to be an optimization for
labels in the memory region 0x2000-0x20FF. That memory region doesn't
have anything special on the Game Boy, and there are no instructions
optimized to read or write from there, so it was probably meant for
another hardware that was supported by ASMotor in the past.

Signed-off-by: AntonioND <antonio_nd@outlook.com>

include/asm/mylink.h

@@ -86,7 +86,10 @@ enum {
 
 	RPN_HRAM,
 
-	RPN_PCEZP,
+	/* TODO: This hasn't been removed in order not to break compatibility
+	 * with the existing object files, but it will be removed in a future
+	 * version. */
+	RPN_unused,
 
 	RPN_RANGECHECK,
 

include/link/mylink.h

@@ -44,7 +44,10 @@ enum eRpnData {
 
 	RPN_HRAM,
 
-	RPN_PCEZP,
+	/* TODO: This hasn't been removed in order not to break compatibility
+	 * with the existing object files, but it will be removed in a future
+	 * version. */
+	RPN_unused,
 
 	RPN_RANGECHECK,
 

src/link/patch.c

@@ -175,15 +175,6 @@ calcrpn(struct sPatch * pPatch)
 				    pPatch->pzFilename, pPatch->nLineNo);
 			}
 			break;
-		case RPN_PCEZP:
-			t = rpnpop();
-			rpnpush(t & 0xFF);
-			if (t < 0x2000 || t > 0x20FF) {
-				errx(1,
-				    "%s(%ld) : Value must be in the ZP area",
-				    pPatch->pzFilename, pPatch->nLineNo);
-			}
-			break;
 		case RPN_CONST:
 			/* constant */
 			t = (*rpn++);