ANDROID: goldfish_pipe: fix call_kern.cocci warnings

Function get_free_pipe_id_locked called on line 671 inside lock on line
669 but uses GFP_KERNEL.  Replace with GFP_ATOMIC.

Generated by: scripts/coccinelle/locks/call_kern.cocci

CC: Yurii Zubrytskyi <zyy@google.com>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Guenter Roeck <groeck@chromium.org>