There are missing parameters in help which fpga dump command
requires.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
           "loadable FPGA image support",
           "[operation type] [device number] [image address] [image size]\n"
           "fpga operations:\n"
-          "  dump\t[dev]\t\t\tLoad device to memory buffer\n"
+          "  dump\t[dev] [address] [size]\tLoad device to memory buffer\n"
           "  info\t[dev]\t\t\tlist known device information\n"
           "  load\t[dev] [address] [size]\tLoad device from memory buffer\n"
 #if defined(CONFIG_CMD_FPGA_LOADP)