soc/intel/apollolake: Correct enum for PrimaryVideoAdaptor FSP parameter

Commit 1a4496e79f (soc/{apl,glk}: Allow to select the primary graphics
device) adds code to set the FSP parameter 'PrimaryVideoAdaptor' based
on the enum description of the FspmUpd.h for Apollo Lake.

Unfortunately, the comment in the header file does not match the
implementation in the FSP and hence setting PrimaryVideoAdaptor to
'GPU_PRIMARY_IGD' will be treated as if the selection was
'GPU_PRIMARY_PCI'. This in turn leads to Linux gfx driver issues for
earlier driver implementations.

This commit corrects the enum values for the FSP parameter to match the
implementation.

TEST=Boot into Linux on mc_apl1 and verify that graphics works.

Change-Id: Iedbc144fa809f6d4587f5223b235ee95579c48f7
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62889
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Maxim Polyakov <max.senia.poliak@gmail.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>

src/soc/intel/apollolake/romstage.c

@@ -232,8 +232,8 @@ static void check_full_retrain(const FSPM_UPD *mupd)
 static void soc_gpu_init_params(FSPM_UPD *mupd)
 {
 	enum {
-		GPU_PRIMARY_IGD = 2,
+		GPU_PRIMARY_IGD = 0,
-		GPU_PRIMARY_PCI = 3,
+		GPU_PRIMARY_PCI = 1,
 	};
 	/* Select primary GPU device */
 	if (CONFIG(ONBOARD_VGA_IS_PRIMARY) && is_devfn_enabled(SA_DEVFN_IGD))