util/inteltool/ivy_memory.c: Properly mask tAONPD

This field is only 4 bits wide.

Change-Id: I2cb746e98176d58fc5be423e18babdaa8801b096
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47749
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/util/inteltool/ivy_memory.c b/util/inteltool/ivy_memory.c
index 7a81a92..3836c11 100644
--- a/util/inteltool/ivy_memory.c
+++ b/util/inteltool/ivy_memory.c
@@ -158,7 +158,7 @@
 			reg = read_mchbar32(0x400c + channel * 0x400);
 			tXPDLL[channel] = reg & 0x1f;
 			tXP[channel] = (reg >> 5) & 7;
-			tAONPD[channel] = (reg >> 8) & 0xff;
+			tAONPD[channel] = (reg >> 8) & 0xf;
 		}
 	printf(".mobile = %d,\n", (mr0[0] >> 12) & 1);
 	print_time("CAS", CAS, tCK);