drivers/intel/gma: Add Kconfig option for vbt data size

From Tigerlake FSP v3373 onwards vbt binary size changed from 8KiB
to 9KiB. Commit cf5d58328fe004d967466be42de62d6bab4c3133 had changed
the size from 8 to 9 Kib. This change adds Kconfig option to choose
vbt data size based on platform.

BUG=b:171401992
BRANCH=none
TEST=build and boot delbin and verify fw screen is loaded

Signed-off-by: Srinidhi N Kaushik <srinidhi.n.kaushik@intel.com>
Change-Id: Ia294fc94ce759666fb664dfdb910ecd403e6a2e9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47151
Reviewed-by: Wonkyu Kim <wonkyu.kim@intel.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/drivers/intel/gma/opregion.c b/src/drivers/intel/gma/opregion.c
index 8f1d2e6..ea05124 100644
--- a/src/drivers/intel/gma/opregion.c
+++ b/src/drivers/intel/gma/opregion.c
@@ -19,7 +19,7 @@
 	return "vbt.bin";
 }
 
-static char vbt_data[9 * KiB];
+static char vbt_data[CONFIG_VBT_DATA_SIZE_KB * KiB];
 static size_t vbt_data_sz;
 
 void *locate_vbt(size_t *vbt_size)