plugin/amdgpu: set errno in open_img_file() on read/write failure

open_img_file() can return NULL after a read_fp() or write_fp()
failure without setting errno. The openat() and fdopen() paths
set errno, but the read/write path does not, so callers using
-errno get zero or a stale value. Set errno to EIO on this path
so errno is always valid when the function returns NULL.

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

plugins/amdgpu/amdgpu_plugin_util.c

@@ -262,6 +262,7 @@ FILE *open_img_file(char *path, bool write, size_t *size, bool expect_present)
 	if (ret) {
 		pr_err("%s:Failed to access file size\n", path);
 		fclose(fp);
+		errno = EIO;
 		return NULL;
 	}