soc: ti: k3-ringacc: add request pair of rings api.

Add new API k3_ringacc_request_rings_pair() to request pair of rings at
once, as in the most case Rings are used with DMA channels which required
to request pair of rings - one to feed DMA with descriptors (TX/RX FDQ) and
one to receive completions (RX/TX CQ). This will allow to simplify Ringacc
API users.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>