nb/intel/sandybridge: Rename and refactor `discover_timC_write`

This is actually aggressive write training, similar to aggressive read
training. Rename it accordingly and refactor it to improve clarity.

Enabling IOSAV_n_SPECIAL_COMMAND_ADDR optimizations must only be done
for later Ivy Bridge steppings. Therefore, guard the code accordingly.

Change-Id: Ia3331b95c265113d94cb5d66c57a97cb77fc3dc9
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47748
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/northbridge/intel/sandybridge/raminit_native.c b/src/northbridge/intel/sandybridge/raminit_native.c
index eecd938..aec6a85 100644
--- a/src/northbridge/intel/sandybridge/raminit_native.c
+++ b/src/northbridge/intel/sandybridge/raminit_native.c
@@ -706,7 +706,7 @@
 		if (err)
 			return err;
 
-		err = discover_timC_write(ctrl);
+		err = aggressive_write_training(ctrl);
 		if (err)
 			return err;