baytrail: pcie: Root port initialization

Add PCIe driver to initialize root ports.

BUG=chrome-os-partner:24111
TEST=Manual on Rambi. Verify that PCIe Wifi card is detected and able to
detect networks.
BRANCH=None.

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>

Change-Id: I3c68da5f27cd162e112add488bdf5ced192b7d12
Reviewed-on: https://chromium-review.googlesource.com/177652
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Commit-Queue: Shawn Nematbakhsh <shawnn@chromium.org>
Tested-by: Shawn Nematbakhsh <shawnn@chromium.org>
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/4981
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/soc/intel/baytrail/Makefile.inc

@@ -42,6 +42,7 @@ ramstage-y += lpe.c
 ramstage-y += scc.c
 ramstage-y += emmc.c
 ramstage-y += lpss.c
+ramstage-y += pcie.c
 
 # Remove as ramstage gets fleshed out
 ramstage-y += placeholders.c