No longer generate separate netboot image for obmc-phosphor-image

The netboot image consists of the initrd and rootfs packaged together
into a single U-Boot legacy ramdisk image.  The initrd is already built
as a U-Boot legacy image via INITRAMFS_IMAGE_TYPES.  Similarly, the
rootfs is already built as a U-Boot legacy image via IMAGE_TYPES.  In
getting rid of the redundancy, using built-in mechanisms is preferred
over custom code thus netboot image is being removed.

Note that removing the netboot image generation means the raw initramfs
CPIO archive is not explicitly needed so it has been removed from
INITRAMFS_IMAGE_TYPES.  It will still be generated as the U-Boot ramdisk
generation requires it as an implicit dependency.

Change-Id: I0370ccc9575000de3238af07f7f14faa283edc15
Signed-off-by: Rick Altherr <raltherr@google.com>
diff --git a/conf/machine/include/obmc-bsp-common.inc b/conf/machine/include/obmc-bsp-common.inc
index e52d8a3..657e54f 100644
--- a/conf/machine/include/obmc-bsp-common.inc
+++ b/conf/machine/include/obmc-bsp-common.inc
@@ -20,7 +20,7 @@
 IMAGE_CLASSES += "obmc-phosphor-image_types_uboot"
 
 INITRAMFS_CTYPE ?= "lzma"
-INITRAMFS_FSTYPES += "cpio.${INITRAMFS_CTYPE} cpio.${INITRAMFS_CTYPE}.u-boot"
+INITRAMFS_FSTYPES += "cpio.${INITRAMFS_CTYPE}.u-boot"
 
 MACHINE_FEATURES_BACKFILL_CONSIDERED = "qemu-usermode"