rework menu so that it can support multiline titles ...

Signed-off-by: Aleksey Kuleshov <rndfax@yandex.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

properly remove menu entry ...

Signed-off-by: Aleksey Kuleshov <rndfax@yandex.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fix double free ...

it already gets free in bootentries_free
no need to do this in ->release method

Signed-off-by: Aleksey Kuleshov <rndfax@yandex.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

boot: add single quotes when printing boot target names ...

It's nicer to read when target names have quotes around them, it
makes it clear that this is a string passed in somewhere.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

boot: Move code to common/ ...

Normally code in commands/ shall only do the option parsing whereas the
functionality shall be in common/ to make the code usable from C aswell.
Do this in the boot code aswell, move it to common/boot.c and add the
function prototypes to include/boot.h

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>