image.bbclass: drop initramfs bundle related code

The original purpose of this code snippet was to repackage initramfs
bundled kernel images before do_image_complete, to be able to be
included by rootfs, but it's not going to achieve that since the
initramfs bundled kernel images are not even installed to ${D}/boot
after commit a49569e3a7534779bbe3f01a0647fd076c95798d:
[ kernel.bbclass: do not copy bundled initramfs to /boot ]

So there is not a initramfs bundled kernel package at all, we should
drop the code, because it is leading kernel do_initramfs_bundle
unnecessarily rerun and it's very time consuming and hence is impacting
the performance a lot.

(From OE-Core rev: eca501aeb4f2cc9255fabab14c68f6910367aaf9)

Signed-off-by: Ming Liu <peter.x.liu@external.atlascopco.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/image.bbclass

@@ -171,10 +171,6 @@ python () {
     d.setVar('IMAGE_FEATURES', ' '.join(sorted(list(remain_features))))
 
     check_image_features(d)
-    initramfs_image = d.getVar('INITRAMFS_IMAGE') or ""
-    if initramfs_image != "":
-        d.appendVarFlag('do_build', 'depends', " %s:do_bundle_initramfs" %  d.getVar('PN'))
-        d.appendVarFlag('do_bundle_initramfs', 'depends', " %s:do_image_complete" % initramfs_image)
 }
 
 IMAGE_CLASSES += "image_types"
@@ -613,15 +609,6 @@ do_package_write_ipk[noexec] = "1"
 do_package_write_deb[noexec] = "1"
 do_package_write_rpm[noexec] = "1"
 
-# Allow the kernel to be repacked with the initramfs and boot image file as a single file
-do_bundle_initramfs[depends] += "virtual/kernel:do_bundle_initramfs"
-do_bundle_initramfs[nostamp] = "1"
-do_bundle_initramfs[noexec] = "1"
-do_bundle_initramfs () {
-	:
-}
-addtask bundle_initramfs after do_image_complete
-
 # Prepare the root links to point to the /usr counterparts.
 create_merged_usr_symlinks() {
     root="$1"