nb/intel/nehalem: Rename to ironlake

The code is for Arrandale CPUs, whose System Agent is Ironlake.

This change simply replaces `nehalem` with `ironlake` and `NEHALEM`
with `IRONLAKE`. The remaining `Nehalem` cases are handled later, as
changing some of them would impact the resulting binary.

Tested with BUILD_TIMELESS=1 without adding the configuration options
into the binary, and packardbell/ms2290 does not change.

Change-Id: I8eb96eeb5e69f49150d47793b33e87b650c64acc
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38941
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/docker/coreboot.org-status/board-status.html/tohtml.sh

@@ -470,7 +470,7 @@ EOF
 				;;
 			"")
 				case $northbridge in
-					INTEL_NEHALEM)
+					INTEL_IRONLAKE)
 						cpu_nice="Intel® 1st Gen (Nehalem) Core i3/i5/i7"
 						socket_nice="?";;
 					RDC_R8610)