rockchip: clk: rk3368: define DMA1_SRST_REQ and DMA2_SRST_REQ

rockchip: clk: rk3368: define DMA1_SRST_REQ and DMA2_SRST_REQ

On he RK3368, we need to temporarily disable security on the DMA
engines during TPL and SPL to allow the MMC host to DMA into DRAM.  To
do so, we need to reset the two DMA engines, which in turn requires
the DMA1_SRST_REQ and DMA2_SRST_REQ constants to refer to the
appropriate bits in the CRU.

As the ATF correctly initialises security (and only leaves EL3 after
doing so), this can not pose a security issue.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>