sfc: Check null pointer of rx_queue->page_ring

stable inclusion
from stable-v5.10.89
commit d70b4001ef741e044c7b173b678828c2740bc9cd
bugzilla: 186140 https://gitee.com/openeuler/kernel/issues/I4S8HA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d70b4001ef741e044c7b173b678828c2740bc9cd



--------------------------------

[ Upstream commit bdf1b5c3 ]

Because of the possible failure of the kcalloc, it should be better to
set rx_queue->page_ptr_mask to 0 when it happens in order to maintain
the consistency.

Fixes: 5a6681e2 ("sfc: separate out SFC4000 ("Falcon") support into new sfc-falcon driver")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/r/20211220135603.954944-1-jiasheng@iscas.ac.cn


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>