mb/google/nissa/var/joxer: disable PCIE RP7

joxer removed SD card from all SKUs, thus disable pcie_rp7.

BUG=b:285477026
TEST=USE="project_joxer emerge-nissa coreboot"

Signed-off-by: Mark Hsieh <mark_hsieh@wistron.corp-partner.google.com>
Change-Id: I3486d665ddb1de521ab4e656addb2209055174c7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75658
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

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

@@ -180,6 +180,7 @@ chip soc/intel/alderlake
 				device pci 00.0 on end
 			end
 		end
+		device ref pcie_rp7 off end # PCIE7 no SD card
                 device ref emmc on
 			probe STORAGE STORAGE_EMMC
 		end