parser: fix invalid segment override on EQU FAR pointers

The parser incorrectly treated colons as memory segment overrides inside
EQU directives because of an inverted far_jmp_ok check. This regression
was introduced in commit 8981724. Removing the incorrect negation restores
proper parsing of FAR pointer constants.

Author: alexvoste

asm/parser.c

@@ -1108,7 +1108,17 @@ insn *parse_line(char *buffer, insn *result, const int bits)
                  */
             } else if (mref || !far_jmp_ok) {
                 /* segment override? */
-                mref = true;
+                if (!mref && (!ok_reg || !IS_SREG(value->type))) {
+		 	i = stdscan(NULL, &tokval);
+			goto mref_more;	
+		} else {
+			mref = true;
+			if (!ok_reg || !IS_SREG(value->type)) {
+				nasm_nonfatal("invalid segment override");
+			}
+			i = stdscan(NULL, &tokval);
+			goto mref_more;
+		}
 
                 /*
                  * Process the segment override.