staging: gdm72xx: Modify a struct allocation to match coding standards

Fixes the following checkpatch.pl issue:

CHECK: Prefer kmalloc(sizeof(*entry)...) over kmalloc(sizeof(struct qos_entry_s)...)

Signed-off-by: Michalis Pappas <mpappas@fastmail.fm>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>