OMAP:DSSCOMP:Limit modedb_len in query ioctl

Add an argument sanity check/limit to prevent
heap corruption attacks.

Change-Id: Ib466af13dba8da6bd4d9b326cdc6b842c8f3caa7
Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@ti.com>