cpts: fix build error by removing useless code.

The cpts driver tries to obtain the input clock frequency by calling the
clock's internal 'recalc' method. Since <plat/clock.h> has been removed,
this code can no longer compile.

However, the driver never makes use of the frequency value, so this patch
fixes the issue by removing the offending code altogether.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>