kexec-tools: reinstate 'kexec-tools' package

kexec-tools: reinstate 'kexec-tools' package

The vmcore commit emptied out ${PN} leading to things like:

	Collected errors:
	 * opkg_install_cmd: Cannot install package kexec-tools.

Let's do the right thing and make ${PN} an empty meta-package that drags in all tools like people expect it to do.

(From OE-Core rev: 9e4f66ec4921c4886203dce99c105141787cc77b)

Signed-off-by: Koen Kooi <koen.kooi@linaro.org>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>