envfs_load_data needs a pointer to the envfs_super, otherwise it
works on an unitialized struct when detecting the envfs version.

This is broken since:

| commit 0a2a8f7
| Author: Sascha Hauer <s.hauer@pengutronix.de>
| Date:   Thu Feb 20 08:16:01 2014 +0100
|
|     environment: Add function to load envfs from buffer
|
|     Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Grmpf. Most compilers do not issue a warning, only the blackfin
gcc 4.3.5 warns about this.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>