Remove hiface_control_abort() as it is not implemented

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Move the enum about control rates from control.h to control.c

The enum names are not used anywhere else, there is no need to have them
public.

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Change rate_value[] type to u8[]

There is no need for those values to be u16.

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Remove the usb_streaming flag from struct control_runtime

This is a leftover from the 6fire driver, the flag is only set and never
used here.

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Avoid using kzalloc in the initializer

It is more readable to have a separate statement for allocation, next to
checking the return value of the allocation function.

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Rewrite the request type value using symbolic constants

This makes it easier to understand what's going on.

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Fix a parameter inversion when calling usb_control_msg()

usb_control_msg() expects the request value to be before the request
type.

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>