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>

env/nowhere.c

@@ -19,4 +19,5 @@ env_t *env_ptr;
 
 U_BOOT_ENV_LOCATION(nowhere) = {
 	.location	= ENVL_NOWHERE,
+	ENV_NAME("nowhere")
 };