boot: Split pxe label_boot() into two parts

This function is far too long. Split out the part which builds and runs
the bootm/i/z commands into its own function.

Add a function comment for the new label_run_boot() function.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
1 file changed