soc/intel/alderlake: Drop unreferenced `InternalGfx`

This option is not referenced anywhere. Drop it.

Change-Id: Ie59de5399a9b1713109bf334d4ad1d7f7efb91f9
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52104
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/alderlake/chip.h

@@ -149,7 +149,6 @@ struct soc_intel_alderlake_config {
 		IGD_SM_56MB = 0xFD,
 		IGD_SM_60MB = 0xFE,
 	} IgdDvmt50PreAlloc;
-	uint8_t InternalGfx;
 	uint8_t SkipExtGfxScan;
 
 	/* HeciEnabled decides the state of Heci1 at end of boot