vcsm: increment res_stats MAP_FAIL stats before we potentially releas…

…e the resource

resource can be kfree'd when the reference count is zero, so we should
not bump the res_stats of the resource after the vmcs_sm_release_resource
call since the resource may have been kfree'd by this call. Instead, bump
the stats before we call vmcs_sm_release_resource to avoid a potential
NULL pointer derefernce.

Bug found using cppcheck static analysis:

[drivers/char/broadcom/vc_sm/vmcs_sm.c:1373]: (error) Dereferencing
  'resource' after it is deallocated / released

Signed-off-by: Colin Ian King <colin.king@canonical.com>

drivers/char/broadcom/vc_sm/vmcs_sm.c

@@ -1368,8 +1368,8 @@ static int vc_sm_mmap(struct file *file, struct vm_area_struct *vma)
 	return 0;
 
 error:
-	vmcs_sm_release_resource(resource, 0);
 	resource->res_stats[MAP_FAIL]++;
+	vmcs_sm_release_resource(resource, 0);
 	return ret;
 }