USB: rndis: Protect rndis response queue

RNDIS response queue addition and deletion can be
performed from rndis completion handler as well
as ioctl from netd to do eth stop. There is a chance
when response queue list can get corrupted by simultaneous
delete and addition performed from rndis_command_compete
and rndis_indicate_status_msg.

Protect access to response queue whenever addition
or deletion is performed by spinlock as the access
may be done from interrupt context as well.

CRs-Fixed: 672582
Change-Id: I74525ee9c8b31bf85063f41ae7c52ab55e9a2b7a
Signed-off-by: Sujeet Kumar <ksujeet@codeaurora.org>