target/configfs: Remove unnecessary null test

This patch removes the null test on lun_cg. lun_cg is initialized
at the beginning of the function to &lun->lun_group. Since lun_cg is
dereferenced prior to the null test, it must be a valid pointer.

The following Coccinelle script is used for detecting the change:

@r@
expression e,f;
identifier g,y;
statement S1,S2;
@@

*e = &f->g
<+...
 f->y
 ...+>
*if (e != NULL || ...)
 S1 else S2

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_fabric_configfs.c

@@ -917,7 +917,6 @@ static struct config_group *target_fabric_make_lun(
 
 	return &lun->lun_group;
 out:
-	if (lun_cg)
 	kfree(lun_cg->default_groups);
 	return ERR_PTR(errno);
 }