This commit adds two new IOCTL commnands for ADC driver. Command
ANIOC_RESET_FIFO resets FIFO head and tail which causes the driver
to wait for the new data to be received. Calling this command before
reading ADC data in user space ensures that the read data are newly
sampled.
Command ANIOC_SAMPLES_ON_READ return the number of read channels in
the buffer. This can be useful in nonblocking mode when the application
needs to get the samples received before the app was started.
Both IOCTL commands are used only in generic driver section only and do
not have any effect on existing architecture specific drivers.
Signed-off-by: Michal Lenc <michallenc@seznam.cz>