General help message cleanup

Many of the help messages were not really helpful; for example, many
commands that take no arguments would not print a correct synopsis
line, but "No additional help available." which is not exactly wrong,
but not helpful either.

Commit ``Make "usage" messages more helpful.'' changed this
partially. But it also became clear that lots of "Usage" and "Help"
messages (fields "usage" and "help" in struct cmd_tbl_s respective)
were actually redundant.

This patch cleans this up - for example:

Before:
	=> help dtt
	dtt - Digital Thermometer and Thermostat

	Usage:
	dtt         - Read temperature from digital thermometer and thermostat.

After:
	=> help dtt
	dtt - Read temperature from Digital Thermometer and Thermostat

	Usage:
	dtt

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/amcc/makalu/cmd_pll.c b/board/amcc/makalu/cmd_pll.c
index 6b38493..9bae67e 100644
--- a/board/amcc/makalu/cmd_pll.c
+++ b/board/amcc/makalu/cmd_pll.c
@@ -291,7 +291,7 @@
 	RCONF: Read current eeprom configuration.      \n\
 	-----------------------------------------------\n\
 	WTEST: Test EEPROM write with predefined values\n\
-	-----------------------------------------------\n"
-	);
+	-----------------------------------------------"
+);
 
 #endif	/* CONFIG_CMD_EEPROM */