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/common/cmd_dcr.c b/common/cmd_dcr.c
index 7aed06c..4f23b8d 100644
--- a/common/cmd_dcr.c
+++ b/common/cmd_dcr.c
@@ -224,22 +224,22 @@
 U_BOOT_CMD(
 	getdcr,	2,	1,	do_getdcr,
 	"Get an AMCC PPC 4xx DCR's value",
-	"dcrn - return a DCR's value.\n"
+	"dcrn - return a DCR's value."
 );
 U_BOOT_CMD(
 	setdcr,	2,	1,	do_setdcr,
 	"Set an AMCC PPC 4xx DCR's value",
-	"dcrn - set a DCR's value.\n"
+	"dcrn - set a DCR's value."
 );
 
 U_BOOT_CMD(
 	getidcr,	3,	1,	do_getidcr,
 	"Get a register value via indirect DCR addressing",
-	"adr_dcrn[.dat_dcrn] offset - write offset to adr_dcrn, read value from dat_dcrn.\n"
+	"adr_dcrn[.dat_dcrn] offset - write offset to adr_dcrn, read value from dat_dcrn."
 );
 
 U_BOOT_CMD(
 	setidcr,	4,	1,	do_setidcr,
 	"Set a register value via indirect DCR addressing",
-	"adr_dcrn[.dat_dcrn] offset value - write offset to adr_dcrn, write value to dat_dcrn.\n"
+	"adr_dcrn[.dat_dcrn] offset value - write offset to adr_dcrn, write value to dat_dcrn."
 );