pik_clock: fix compiler warning when building with GCC-7 compiler
Created by: manojkumar-arm
This patch fixes compiler warning that arises when building firmware without css_clock module and with GCC 7 compiler.
Change-Id: I5b55a51ac4de827a2ae7332043efa92edf4853da Signed-off-by: Manoj Kumar manoj.kumar3@arm.com