net: dhcp: allow to set transmitted vendor id ...

For net boot setups it is useful to submit boot params like server or
bootfile over dhcp. To distinguish barebox from e.g. pxe machines,
a custom vendor id can be sent in dhcp discover/request messages.

E.g. the ISC dhcp server can be configured with

| if substring(option vendor-class-identifier,0,8) = "barebox:" {
|       next-server             192.168.3.24;
|       server-name             "192.168.3.24";
|       option tftp-server-name "192.168.3.24";
|       option root-path = concat("/srv/sysroots/by-mac/",
|          binary-to-ascii (16, 8, "-", substring (hardware, 1, 6)));
| }

to sent boot params which are valid for barebox hosts only.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Jean-Christophe PLAGNIOL-VILLARD:
 - update the use dhcp command option
 - support to set the vendor via env dhcp_vendor_id
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

defaultenv: simplify boot ...

Now that we have a bootm command which boots everything we can
simplify the defaultenvironment. We can call bootm on every
image type and can remove the kernelimage_type variables.

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

defaultenv: place eth0.ethaddr more visibly ...

The config file looks like you just need to set ethaddr when you do
static IP. This is misleading, so put the setting to a more prominent
place.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

defaultenv: add config template ...

This patch add a config template to the defaultenv.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>