mb/google/rex/var/karis: Add PANEL_PWRSEQ_EC_CONTROL in fw_config

Only EC will use field "PANEL_PWRSEQ_EC_CONTROL".
Add this field in coreboot for align fw_config settings.

BUG=b:314245238
TEST=emerge coreboot pass

Change-Id: Icecb44a338ddc28027e362332c6a69cc9fd268d5
Signed-off-by: Tyler Wang <tyler.wang@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79570
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: YH Lin <yueherngl@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/rex/variants/karis/overridetree.cb

@@ -29,6 +29,10 @@ fw_config
 		option WIFI_CNVI		0
 		option WIFI_PCIE		1
 	end
+	field PANEL_PWRSEQ_EC_CONTROL 14
+		option DISABLE			0
+		option ENABLE			1
+	end
 end
 
 chip soc/intel/meteorlake