Improve license declaration for cmd_ini.h

Instead of referenceing the source webpage (which can change) include
the license in the source file.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reported-by: Igor Grinberg <grinberg@compulab.co.il>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Tom Rini <trini@ti.com>
Cc: Wolfgang Denk <wd@denx.de>
Acked-by: Wolfgang Denk <wd@denx.de>