env: make env_import(_redund) return 0 on success, not 1

env_import (and env_import_redund) currently return 1 on success
and 0 on error. However, they are only used from functions
returning 0 on success or a negative value on error.

Let's clean this up by making env_import and env_import_redund
return 0 on success and -EIO on error (as was the case for all
users before).

Users that cared for the return value are also updated. Funny
enough, this only affects onenand.c and sf.c

Signed-off-by: Simon Goldschmidt <sgoldschmidt@de.pepperl-fuchs.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/env/sf.c b/env/sf.c
index a2e4c93..3dc5441 100644
--- a/env/sf.c
+++ b/env/sf.c
@@ -236,7 +236,7 @@
 		ep = tmp_env2;
 
 	ret = env_import((char *)ep, 0);
-	if (!ret) {
+	if (ret) {
 		pr_err("Cannot import environment: errno = %d\n", errno);
 		set_default_env("!env_import failed");
 	}
@@ -336,7 +336,7 @@
 	}
 
 	ret = env_import(buf, 1);
-	if (ret)
+	if (!ret)
 		gd->env_valid = ENV_VALID;
 
 err_read: