c_rt_ctx is used to store current SP before the system goes
into suspend. The assert for its value being zero is not
really necessary as the value gets over-written eventually.

This patch removes assert(tlk_ctx->c_rt_ctx == 0) from the
System Suspend path, as a result.

Change-Id: If41f15e74ebbbfd82958d8e179114899b2ffb0a7
Signed-off-by: Mihir Joshi <mihirj@nvidia.com>