pcie_aer: Fix help message of pcie_aer_inject_error command

There is an interesting typo in the help message of pcie_aer_inject_error
command. Use 'tlp' instead of 'tlb' to match the PCIe AER term.

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Message-Id: <20201204030953.837-1-yuzenghui@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hmp-commands.hx

@@ -1302,8 +1302,8 @@ ERST
 	              " -c for correctable error\n\t\t\t"
                       "<id> = qdev device id\n\t\t\t"
                       "<error_status> = error string or 32bit\n\t\t\t"
-                      "<tlb header> = 32bit x 4\n\t\t\t"
-                      "<tlb header prefix> = 32bit x 4",
+                      "<tlp header> = 32bit x 4\n\t\t\t"
+                      "<tlp header prefix> = 32bit x 4",
         .cmd        = hmp_pcie_aer_inject_error,
     },