mb/google/brya/var/agah: Reenable ASPM L1 substates

Now that the GPU CLKREQ# signal is working correctly, ASPM L1 substates
can be enabled and appear functional.

BUG=b:240390998
TEST=lspci reports them as functional, MODS does not hang

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I8297f6bbf7f5a1f7d4ac519bc5b7b3112a74a9a0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66811
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Ivy Jian <ivy.jian@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

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

@@ -81,7 +81,6 @@ chip soc/intel/alderlake
 				.clk_req = 0,
 				.clk_src = 0,
 				.flags = PCIE_RP_LTR | PCIE_RP_AER,
-				.pcie_rp_aspm = ASPM_L0S,
 			}"
 			device pci 00.0 alias dgpu on end
 		end