ddr: fsl: Merge macro CONFIG_NUM_DDR_CONTROLLERS and CONFIG_SYS_NUM_DDR_CTRLS

These two macros are used for the same thing, the total number of DDR
controllers for a given SoC. Use SYS_NUM_DDR_CTRLS in Kconfig and
merge existing usage.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/drivers/ddr/fsl/ctrl_regs.c b/drivers/ddr/fsl/ctrl_regs.c
index f7e87b8..21687dd 100644
--- a/drivers/ddr/fsl/ctrl_regs.c
+++ b/drivers/ddr/fsl/ctrl_regs.c
@@ -2318,17 +2318,17 @@
 	case 0:
 		ddrc = (void *)CONFIG_SYS_FSL_DDR_ADDR;
 		break;
-#if defined(CONFIG_SYS_FSL_DDR2_ADDR) && (CONFIG_NUM_DDR_CONTROLLERS > 1)
+#if defined(CONFIG_SYS_FSL_DDR2_ADDR) && (CONFIG_SYS_NUM_DDR_CTLRS > 1)
 	case 1:
 		ddrc = (void *)CONFIG_SYS_FSL_DDR2_ADDR;
 		break;
 #endif
-#if defined(CONFIG_SYS_FSL_DDR3_ADDR) && (CONFIG_NUM_DDR_CONTROLLERS > 2)
+#if defined(CONFIG_SYS_FSL_DDR3_ADDR) && (CONFIG_SYS_NUM_DDR_CTLRS > 2)
 	case 2:
 		ddrc = (void *)CONFIG_SYS_FSL_DDR3_ADDR;
 		break;
 #endif
-#if defined(CONFIG_SYS_FSL_DDR4_ADDR) && (CONFIG_NUM_DDR_CONTROLLERS > 3)
+#if defined(CONFIG_SYS_FSL_DDR4_ADDR) && (CONFIG_SYS_NUM_DDR_CTLRS > 3)
 	case 3:
 		ddrc = (void *)CONFIG_SYS_FSL_DDR4_ADDR;
 		break;