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/drivers/misc/ds4510.c b/drivers/misc/ds4510.c
index 8b5fbbc..f2510a3 100644
--- a/drivers/misc/ds4510.c
+++ b/drivers/misc/ds4510.c
@@ -404,12 +404,14 @@
 	"ds4510 pullup pin 0|1\n"
 	"	- disable/enable pullup on specified pin\n"
 	"ds4510 nv 0|1\n"
-	"	- make gpio and seeprom writes volatile/non-volatile\n"
+	"	- make gpio and seeprom writes volatile/non-volatile"
 #ifdef CONFIG_CMD_DS4510_RST
+	"\n"
 	"ds4510 rstdelay 0-3\n"
-	"	- set reset output delay\n"
+	"	- set reset output delay"
 #endif
 #ifdef CONFIG_CMD_DS4510_MEM
+	"\n"
 	"ds4510 eeprom read addr off cnt\n"
 	"ds4510 eeprom write addr off cnt\n"
 	"	- read/write 'cnt' bytes at EEPROM offset 'off'\n"
@@ -418,7 +420,7 @@
 	"	- read/write 'cnt' bytes at SRAM-shadowed EEPROM offset 'off'\n"
 	"ds4510 sram read addr off cnt\n"
 	"ds4510 sram write addr off cnt\n"
-	"	- read/write 'cnt' bytes at SRAM offset 'off'\n"
+	"	- read/write 'cnt' bytes at SRAM offset 'off'"
 #endif
 );
 #endif /* CONFIG_CMD_DS4510 */