DA850: Split MMCSD clock into two to support both MMCSD peripherals

Split mmcsd_clk into mmcsd0_clk and mmcsd1_clk and add davinci_mmc.1
in preparation for adding support for MMCSD1 peripheral in DA850.

Signed-off-by: Juha Kuikka <juha.kuikka@elektrobit.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>