ARM: imx: correct gpu2d_axi and gpu3d_axi clock setting
On i.MX6Q, gpu2d_axi and gpu3d_axi are either from AXI or
AHB clock, but on i.MX6DL, gpu2d_axi and gpu3d_axi are
from mmdc_ch0_axi_podf, and they can NOT be gated by mmdc_ch0_axi
's clock gate, the mux option register field(CCM_CBCMR)
is marked as "Reserved" now on i.MX6DL RM, so correct these
two clks setting.