media: staging: atomisp: Remove dead code for MID (#1)

Remove dead code. If someone needs it the P-Unit semaphore is handled by
I2C DesignWare driver (drivers/i2c/busses/i2c-designware-baytrail.c).

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>