imx: mx6: support i.MX6SOLO when enable/disable_ldb_di_clock_sources

i.MX6DL and i.MX6SOLO work the same, add i.MX6SOLO support
when enable/disable_ldb_di_clock_sources.

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>