video: mb862xx-i2c: fix for reliable decoder register access

Increase delay when polling for tx status. This fixes
the unreliable video decoder i2c register access.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>