bootm: Support boot measurement

Add a configuration option to measure the boot through the bootm
function. Add the measurement state to the booti and bootz paths
as well.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Ilias: Added some info on Kconfig explaining this is when booting !EFI
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>