ice: dpll: Fix compilation warning

Introduced by commit ad1df4f2d591 ("ice: dpll: Support E825-C SyncE and
dynamic pin discovery"):

ice_dpll.c: In function 'ice_dpll_init':
ice_dpll.c:3588:59: error: '%u' directive output may be truncated
writing between 1 and 10 bytes into a region of size 4
[-Werror=format-truncation=] snprintf(pin_name, sizeof(pin_name),
"rclk%u", i);

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Przemyslaw Korba <przemyslaw.korba@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>