Command upgrading introduced two off-by-one bugs in the flash commands.
This patch fixes the 'flash {protect,erase_sector}' commands to check
that they have been passed the correct number of arguments.
Ammended during commit to fix help text for 'erase_address' too.
 
 COMMAND_HANDLER(handle_flash_erase_command)
 {
-       if (CMD_ARGC != 2)
+       if (CMD_ARGC != 3)
                return ERROR_COMMAND_SYNTAX_ERROR;
 
        uint32_t bank_nr;
 
 COMMAND_HANDLER(handle_flash_protect_command)
 {
-       if (CMD_ARGC != 3)
+       if (CMD_ARGC != 4)
                return ERROR_COMMAND_SYNTAX_ERROR;
 
        uint32_t bank_nr;
                .name = "erase_address",
                .handler = &handle_flash_erase_address_command,
                .mode = COMMAND_EXEC,
-               .usage = "<bank> <address> <length>",
+               .usage = "<address> <length>",
                .help = "erase address range",
 
        },