qemu-char: Fix use of free() instead of g_free()

cppcheck reported these errors:

qemu-char.c:1667: error: Mismatching allocation and deallocation: s
qemu-char.c:1668: error: Mismatching allocation and deallocation: chr
qemu-char.c:1769: error: Mismatching allocation and deallocation: s
qemu-char.c:1770: error: Mismatching allocation and deallocation: chr
Tested-by: NDongxu Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

qemu-char.c

@@ -1664,8 +1664,8 @@ static int qemu_chr_open_win(QemuOpts *opts, CharDriverState **_chr)
     chr->chr_close = win_chr_close;
 
     if (win_chr_init(chr, filename) < 0) {
-        free(s);
-        free(chr);
+        g_free(s);
+        g_free(chr);
         return -EIO;
     }
     qemu_chr_generic_open(chr);
@@ -1766,8 +1766,8 @@ static int qemu_chr_open_win_pipe(QemuOpts *opts, CharDriverState **_chr)
     chr->chr_close = win_chr_close;
 
     if (win_chr_pipe_init(chr, filename) < 0) {
-        free(s);
-        free(chr);
+        g_free(s);
+        g_free(chr);
         return -EIO;
     }
     qemu_chr_generic_open(chr);