mb/google/nissa/var/sundance: disable pcie port7

Disable pcie port7 to prevent s0ix issue when run the FAFT sleep test.

BUG=b:328147465
TEST=Build and check S0ix function and verify FAFT sleep funciton.

Change-Id: I53f704ed11a5c63b5c079c6e60ce2fa32bbd8b1a
Signed-off-by: Roger Wang <roger2.wang@lcfc.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83057
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>

src/mainboard/google/brya/variants/sundance/overridetree.cb

@@ -273,6 +273,7 @@ chip soc/intel/alderlake
 				device pci 00.0 on end
 			end
 		end
+		device ref pcie_rp7 off end
 		device ref pch_espi on
 			chip ec/google/chromeec
 				use conn0 as mux_conn[0]