fastboot: remove 'powerdown'

This isn't sent by the fastboot client.
This isn't in our bootloader requirement document.
Neither my hikey nor sailfish respond to this.
The README.md literally uses this as an example for 'unknown command'

Test: fastboot still works.
Change-Id: Ia442a41de517dae078dd7e73c951aadb97646c73
diff --git a/fastboot/fuzzy_fastboot/main.cpp b/fastboot/fuzzy_fastboot/main.cpp
index 14bf5bf..60902c4 100644
--- a/fastboot/fuzzy_fastboot/main.cpp
+++ b/fastboot/fuzzy_fastboot/main.cpp
@@ -86,9 +86,8 @@
 
 const std::string DEFAULT_OUPUT_NAME = "out.img";
 // const char scratch_partition[] = "userdata";
-const std::vector<std::string> CMDS{"boot",        "continue", "download:", "erase:",
-                                    "flash:",      "getvar:",  "powerdown", "reboot",
-                                    "set_active:", "upload",   "verify"};
+const std::vector<std::string> CMDS{"boot",    "continue", "download:",   "erase:", "flash:",
+                                    "getvar:", "reboot",   "set_active:", "upload", "verify"};
 
 // For pretty printing we need all these overloads
 ::std::ostream& operator<<(::std::ostream& os, const RetCode& ret) {