cros_bundle_firmware: Fix up coreboot invocation

This should just use the Tool method, and not try to provide its own
full path.

BUG=chromium-os:19724
TEST=manual, in chroot:
PYTHONPATH="~/cosarm/src/platform/dev/host/lib" python ~/cosarm/src/platform/dev/host/cros_bundle_firmware  -u ~/cosarm/chroot/build/link/firmware/u-boot.bin -O out --bootsecure --bootcmd vboot_twostop  -b link --dt ~/u/board/chromebook-x86/coreboot/link.dts -C ~/cosarm/chroot/build/link/firmware/coreboot.rom

Change-Id: I23c6561bc2812a7032bd4a32e110c77ce8ee8609
Reviewed-on: https://gerrit.chromium.org/gerrit/17769
Commit-Ready: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/host/lib/bundle_firmware.py b/host/lib/bundle_firmware.py
index 488eb15..0afa977 100644
--- a/host/lib/bundle_firmware.py
+++ b/host/lib/bundle_firmware.py
@@ -418,18 +418,17 @@
       CmdError if a command fails.
     """
     bootstub = os.path.join(self._tools.outdir, 'coreboot-full.rom')
-    cbfstool = "/usr/bin/cbfstool"
     uboot_elf = uboot.replace(".bin", ".elf")
     shutil.copyfile(coreboot, bootstub)
     if seabios:
-        self._tools.Run(cbfstool, [bootstub, 'add-payload', seabios,
+        self._tools.Run('cbfstool', [bootstub, 'add-payload', seabios,
             'fallback/payload', 'lzma'])
-        self._tools.Run(cbfstool, [bootstub, 'add-payload', uboot_elf,
+        self._tools.Run('cbfstool', [bootstub, 'add-payload', uboot_elf,
             'img/U-Boot', 'lzma'])
     else:
-        self._tools.Run(cbfstool, [bootstub, 'add-payload', uboot_elf,
+        self._tools.Run('cbfstool', [bootstub, 'add-payload', uboot_elf,
             'fallback/payload', 'lzma'])
-    self._tools.Run(cbfstool, [bootstub, 'add', fdt.fname, 'u-boot.dtb',
+    self._tools.Run('cbfstool', [bootstub, 'add', fdt.fname, 'u-boot.dtb',
         '0xac'])
     return bootstub