feat(intel): implement timer init divider via CPU frequency for N5X

Get CPU frequency and update the timer init div with it.
The timer is vary based on the CPU frequency instead of hardcoded.

Signed-off-by: Jit Loon Lim <jit.loon.lim@intel.com>
Signed-off-by: Sieu Mun Tang <sieu.mun.tang@intel.com>
Change-Id: Ibfaa47fb7a25176eebf06f4828bf9729d56f12ed
diff --git a/plat/intel/soc/agilex/include/agilex_clock_manager.h b/plat/intel/soc/agilex/include/agilex_clock_manager.h
index f39d475..8ec8e59 100644
--- a/plat/intel/soc/agilex/include/agilex_clock_manager.h
+++ b/plat/intel/soc/agilex/include/agilex_clock_manager.h
@@ -127,5 +127,6 @@
 uint32_t get_wdt_clk(void);
 uint32_t get_uart_clk(void);
 uint32_t get_mmc_clk(void);
+uint32_t get_cpu_clk(void);
 
 #endif