cleanup: qemu_capabilities: remove redundant error messages

We reported error in caller virQEMUCapsCacheLookupByArch.
So the same error messages in qemuConnectGetDomainCapabilities
is useless.
Signed-off-by: NChen Hanxiao <chenhanxiao@gmail.com>

src/qemu/qemu_driver.c

@@ -18713,12 +18713,8 @@ qemuConnectGetDomainCapabilities(virConnectPtr conn,
     } else {
         if (!(qemuCaps = virQEMUCapsCacheLookupByArch(caps,
                                                       driver->qemuCapsCache,
-                                                      arch))) {
-            virReportError(VIR_ERR_INVALID_ARG,
-                           _("unable to find any emulator to serve '%s' "
-                             "architecture"), virArchToString(arch));
+                                                      arch)))
             goto cleanup;
-        }
 
         emulatorbin = virQEMUCapsGetBinary(qemuCaps);
     }