cmd: Convert existing long help messages to the new macro

- Generally we just drop the #ifdef CONFIG_SYS_LONGHELP and endif lines
  and use U_BOOT_LONGHELP to declare the same variable name as before
- In a few places, either rename the variable to follow convention or
  introduce the variable as it was being done inline before.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/sandbox/exception.c b/cmd/sandbox/exception.c
index 1aa1d67..c082401 100644
--- a/cmd/sandbox/exception.c
+++ b/cmd/sandbox/exception.c
@@ -31,11 +31,10 @@
 			 "", ""),
 };
 
-static char exception_help_text[] =
+U_BOOT_LONGHELP(exception,
 	"<ex>\n"
 	"  The following exceptions are available:\n"
 	"  undefined  - undefined instruction\n"
-	"  sigsegv    - illegal memory access\n"
-	;
+	"  sigsegv    - illegal memory access\n");
 
 #include <exception.h>