mb/starlabs/starbook/mtl: Set PsysPmax to auto

Set PsysPmax to 0, which is auto instead of the FSP default
which is 21.5W (0xac).

Change-Id: Ia2503077067fa719a09f9877d7fe0bedf2a662f1
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/87006
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>

src/mainboard/starlabs/starbook/variants/mtl/romstage.c

@@ -37,4 +37,5 @@ void mainboard_memory_init_params(FSPM_UPD *mupd)
 		mupd->FspmConfig.PcieRpEnableMask &= ~(1 << 8);
 
 	mupd->FspmConfig.PchHdaSubSystemIds = 0x70381e50;
+	mupd->FspmConfig.PsysPmax = 0;
 };