vl: drop needless -spice checks

Since commit 5324e3e958e ("qemu-options: define -spice only #ifdef
CONFIG_SPICE"), it is unnecessary to check at runtime for "-spice"
option.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
diff --git a/system/vl.c b/system/vl.c
index 3fb5692..fb0389e 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -3475,12 +3475,7 @@
                 break;
 #ifdef CONFIG_SPICE
             case QEMU_OPTION_spice:
-                olist = qemu_find_opts_err("spice", NULL);
-                if (!olist) {
-                    error_report("spice support is disabled");
-                    exit(1);
-                }
-                opts = qemu_opts_parse_noisily(olist, optarg, false);
+                opts = qemu_opts_parse_noisily(qemu_find_opts("spice"), optarg, false);
                 if (!opts) {
                     exit(1);
                 }