fix(xilinx): resolve misra rule 8.6 violations

Fixed below MISRA violation:
- MISRA Violation: MISRA-C:2012 R.8.6:
  - An identifier with external linkage shall have exactly one external
    definition.
- Fix:
  - Removed redundant function declarations since it is not defined.

Change-Id: If003efbfa08ee6ff4f545605ef34dfd16f33b664
Signed-off-by: Devanshi Chauhan Alpeshbhai <devanshi.chauhanalpeshbhai@amd.com>
diff --git a/plat/xilinx/common/include/pm_api_sys.h b/plat/xilinx/common/include/pm_api_sys.h
index 3efd7ed..793b270 100644
--- a/plat/xilinx/common/include/pm_api_sys.h
+++ b/plat/xilinx/common/include/pm_api_sys.h
@@ -41,20 +41,10 @@
 enum pm_ret_status pm_get_callbackdata(uint32_t *data, size_t count, uint32_t flag,
 			 uint32_t ack);
 void pm_client_set_wakeup_sources(uint32_t node_id);
-enum pm_ret_status pm_pll_set_param(uint32_t clk_id, uint32_t param,
-				    uint32_t value, uint32_t flag);
-enum pm_ret_status pm_pll_get_param(uint32_t clk_id, uint32_t param,
-				    uint32_t *value, uint32_t flag);
-enum pm_ret_status pm_pll_set_mode(uint32_t clk_id, uint32_t mode,
-				   uint32_t flag);
-enum pm_ret_status pm_pll_get_mode(uint32_t clk_id, uint32_t *mode,
-				   uint32_t flag);
 enum pm_ret_status pm_force_powerdown(uint32_t target, uint8_t ack,
 				      uint32_t flag);
 enum pm_ret_status pm_system_shutdown(uint32_t type, uint32_t subtype,
 				      uint32_t flag);
-enum pm_ret_status pm_query_data(uint32_t qid, uint32_t arg1, uint32_t arg2,
-				 uint32_t arg3, uint32_t *data, uint32_t flag);
 uint32_t pm_get_shutdown_scope(void);
 enum pm_ret_status pm_feature_check(uint32_t api_id, uint32_t *ret_payload,
 				    uint32_t flag);