mb/google/herobrine: Add PCIe domain support

Add PCIe domain support for herobrine by enabling it in the devicetree.

BUG=b:182963902,b:216686574,b:181098581
TEST=Verified on Qualcomm sc7280 development board with NVMe card
(Koixa NVMe, Model-KBG40ZPZ256G with FW AEGA0102). Confirmed NVMe is
getting detected in response to 'storage init' command in depthcharge
CLI prompt.

Output logs:
  ->dpch: storage init
    Initializing NVMe controller 1e0f:0001
    Identified NVMe model KBG40ZPZ256G TOSHIBA MEMORY
    Added NVMe drive "NVMe Namespace 1" lbasize:512, count:0x1dcf32b0
    *  0: NVMe Namespace 1
     1 devices total

Also verified NVMe boot path, that is depthcharge is able to load the
kernel image from NVMe storage.

Change-Id: Ied8fbbc8d20698ee081d93ba184b7d0291bb6a76
Signed-off-by: Veerabhadrarao Badiganti <quic_vbadigan@quicinc.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65137
Reviewed-by: Shelley Chen <shchen@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/herobrine/devicetree.cb

@@ -2,4 +2,7 @@
 
 chip soc/qualcomm/sc7280
 	device cpu_cluster 0 on end
+	device domain 0 on
+		device pci 00.0 on end
+	end
 end