zynqmp: pm: Reimplement clock disable EEMI API

Clock disable EEMI API is reimplemented to use system-level clock
and pll EEMI APIs rather than direct MMIO read/write accesses to clock
and pll control registers.
Since linux still uses clock disable API to reset the PLL in the
implementation of pm_clock_disable() we need to workaround this by
distinguishing two cases: 1) if the given clock ID corresponds to a PLL
output clock ID; or 2) given clock ID is truly an on-chip clock that can
be gated.
For case 1) we'll call pm_api_clock_pll_disable() implemented in
pm_api_clock.h/c. This function will reset the PLL using the system-level
PLL set mode EEMI API with the reset mode argument.
For case 2) we'll call the PMU to configure the clock gate. This is done
using system-level clock disable EEMI API.
Functions that appear to be unused after this change is made are removed.

Signed-off-by: Mirela Simonovic <mirela.simonovic@aggios.com>
Acked-by: Will Wong <WILLW@xilinx.com>
Signed-off-by: Jolly Shah <jollys@xilinx.com>
diff --git a/plat/xilinx/zynqmp/pm_service/pm_api_sys.c b/plat/xilinx/zynqmp/pm_service/pm_api_sys.c
index e33761c..fe5828e 100644
--- a/plat/xilinx/zynqmp/pm_service/pm_api_sys.c
+++ b/plat/xilinx/zynqmp/pm_service/pm_api_sys.c
@@ -903,12 +903,20 @@
  * This function is used by master to disable the clock
  * including peripherals and PLL clocks.
  *
- * Return: Returns status, either success or error+reason.
+ * @return:	Error if an argument is not valid or status as returned by the
+ *		pm_clock_gate
  */
-
 enum pm_ret_status pm_clock_disable(unsigned int clock_id)
 {
-	return pm_api_clock_disable(clock_id);
+	struct pm_pll *pll;
+
+	/* First try to handle it as a PLL */
+	pll = pm_clock_get_pll(clock_id);
+	if (pll)
+		return pm_clock_pll_disable(pll);
+
+	/* It's an on-chip clock, PMU should configure clock's gate */
+	return pm_clock_gate(clock_id, 0);
 }
 
 /**