staging: pi433: Redefine F_OSC using units.h macro

Use HZ_PER_MHZ for a more robust definition.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Shahar Avidar <ikobh7@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240227221204.534131-4-ikobh7@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>