ARM: i.MX6: clk: add different DualLite MLB clock config

The CCM_CBCMR register (address 0x02C4018) has different meaning
between the i.MX6 Quad/Dual and the i.MX6 Solo/DualLite.

Compared to the i.MX6 Quad/Dual, the CCM_CBCMR register in the
i.MX6 Solo/DualLite reuses the gpu2d_core bits for the MLB clock
configuration.

Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>