Correct SPL uses of SYS_LONGHELP

This converts 5 usages of this option to the non-SPL form, since there is
no SPL_SYS_LONGHELP defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/dm.c b/cmd/dm.c
index 979cd36..3263547 100644
--- a/cmd/dm.c
+++ b/cmd/dm.c
@@ -84,7 +84,7 @@
 #define DM_MEM
 #endif
 
-#if CONFIG_IS_ENABLED(SYS_LONGHELP)
+#if IS_ENABLED(CONFIG_SYS_LONGHELP)
 static char dm_help_text[] =
 	"compat        Dump list of drivers with compatibility strings\n"
 	"dm devres        Dump list of device resources for each device\n"