PXE: add dhcp option support for better pxe support

	"MAGIC" - 208 - An option whose presence and content verifies to
	the PXELINUX bootloader that the options numbered 209-211 are for
	the purpose as described herein.

	"ConfigFile" - 209 - Configures the path/filename component of the
	configuration file's location, which this bootloader should use to
	configure itself.

	"PathPrefix" - 210 - Configures a value to be prepended to the
	ConfigFile to discern the directory location of the file.

	"RebootTime" - 211 - Configures a timeout after which the
	bootstrap program will reboot the system (most likely returning it
	to PXE).

Signed-off-by: Justin L Werner <justin.werner@caononical.com>
Signed-off-by: John Rigby <john.rigby@linaro.org>
12 files changed