env: Drop the env_name_spec global

Add a name to the driver and use that instead of the global variable
declared by each driver.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/env/nowhere.c b/env/nowhere.c
index 1d2ae85..1a17d69 100644
--- a/env/nowhere.c
+++ b/env/nowhere.c
@@ -19,4 +19,5 @@
 
 U_BOOT_ENV_LOCATION(nowhere) = {
 	.location	= ENVL_NOWHERE,
+	ENV_NAME("nowhere")
 };