env: Drop unused env_ptr variables

This variable is declared as a global in most environment location
drivers. But it is not used outside the drivers and most of the
declarations are unnecessary.

Also some drivers call free() on env_ptr which seems wrong since it is
not in the heap.

Drop the variable where possible, and all calls to free().

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

env/nvram.c

@@ -36,7 +36,6 @@ DECLARE_GLOBAL_DATA_PTR;
 #ifdef CONFIG_SYS_NVRAM_ACCESS_ROUTINE
 extern void *nvram_read(void *dest, const long src, size_t count);
 extern void nvram_write(long dest, const void *src, size_t count);
-env_t *env_ptr;
 #else
 env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
 #endif