[ Upstream commit 0efcc2c0 ]

Same as other i.MX6 SoCs, ensure unused MMDC channel's
handshake is bypassed, this is to make sure no request
signal will be generated when periphe_clk_sel is changed
or SRC warm reset is triggered.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>