haswell/lynxpoint: Drop remaining uses of `ISLP` method

There's no need to dynamically differentiate between traditional and Low
Power platforms at runtime, and doing so makes code reuse more complex.

Change-Id: Id40f2f5f41db00487af9115eabee8874c2399030
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46785
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/haswell/acpi/ctdp.asl b/src/northbridge/intel/haswell/acpi/ctdp.asl
index 84c0f2f..47b7940 100644
--- a/src/northbridge/intel/haswell/acpi/ctdp.asl
+++ b/src/northbridge/intel/haswell/acpi/ctdp.asl
@@ -79,13 +79,13 @@
 	/* Calculate PL2 based on chip type */
 	Method (CPL2, 1, NotSerialized)
 	{
-		If (\ISLP ()) {
-			/* Haswell ULT PL2 = 25W */
-			Return (25 * 8)
-		} Else {
-			/* Haswell Mobile PL2 = 1.25 * PL1 */
-			Return ((Arg0 * 125) / 100)
-		}
+#if CONFIG(INTEL_LYNXPOINT_LP)
+		/* Haswell ULT PL2 = 25W */
+		Return (25 * 8)
+#else
+		/* Haswell Mobile PL2 = 1.25 * PL1 */
+		Return ((Arg0 * 125) / 100)
+#endif
 	}
 
 	/* Set Config TDP Down */