ARMv7: help/usage updates

Provide helptext which was sometimes missing; update some of it
to be more accurate.

Usage syntax messages have the same EBNF as the User's Guide;
there should be no angle brackets in either place.

Don't use "&function"; functions are like arrays, their address
is their name.  Shrink some overlong lines, remove some empties.

Add a couple comments about things that should change:  those
extra TCK cycles for MEM-AP reads are in the wrong place (that
might explain some problems we've seen); the DAP command tables
should be shared, not copied.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/target/cortex_a8.c

@@ -1642,13 +1642,13 @@ COMMAND_HANDLER(cortex_a8_handle_dbginit_command)
 static const struct command_registration cortex_a8_exec_command_handlers[] = {
 	{
 		.name = "cache_info",
-		.handler = &cortex_a8_handle_cache_info_command,
+		.handler = cortex_a8_handle_cache_info_command,
 		.mode = COMMAND_EXEC,
 		.help = "display information about target caches",
 	},
 	{
 		.name = "dbginit",
-		.handler = &cortex_a8_handle_dbginit_command,
+		.handler = cortex_a8_handle_dbginit_command,
 		.mode = COMMAND_EXEC,
 		.help = "Initialize core debug",
 	},