Fix mach64 driver crash

Due to lack of iopl(3), mach64 driver crashes when ior(BUS_CNTL) is
called. Since BUS_CNTL is out of the range 0x0000-0x03ff, ioperm(0,
1024, 1) is not sufficient and the ior() causes access violation.
This patch reintroduce iopl(3) call in the function hwEnableIO().

Addresses: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1110521
Fixes: a0f738a673 ("Fixed ioperm calls in hwEnableIO")
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2052>
(cherry picked from commit 3b39aebf98)

hw/xfree86/os-support/linux/lnx_video.c

@@ -123,8 +123,8 @@ hwEnableIO(void)
     char *buf=NULL, target[5];
     FILE *fp;
 
-    if (ioperm(0, 1024, 1)) {
-        ErrorF("xf86EnableIO: failed to enable I/O ports 0000-03ff (%s)\n",
+    if (ioperm(0, 1024, 1) || iopl(3)) {
+        ErrorF("xf86EnableIO: failed to enable I/O ports access (%s)\n",
                strerror(errno));
         return FALSE;
     }