staging: android: ion: fix sys heap pool's gfp_flags

In the first loop, gfp_flags will be modified to high_order_gfp_flags,
and there will be no chance to change back to low_order_gfp_flags.

Fixes: e7f63771

 ("ION: Sys_heap: Add cached pool to spead up cached buffer alloc")
Signed-off-by: Qing Xia <saberlily.xia@hisilicon.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jing Xia <jing.xia@unisoc.com>
Reviewed-by: Yuming Han <yuming.han@unisoc.com>
Reviewed-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Reviewed-by: Orson Zhai <orson.zhai@unisoc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>