Build: Add "board options" column to boards.cfg

Build: Add "board options" column to boards.cfg

There are some boards where it's currently not possible to detect all
board information at runtime, therefore a new column was added to
boards.cfg .

This column can contain multiple options: a board configuration name,
optionally followed by a colon (':') and a list of options, which are
separated by comma (',').

In case of simple options like '256M_U_BOOT', these expand to
"#define CONFIG_MK_256M_U_BOOT 1" in config.h . In case of
assignments like 'RAM=8192', these expand to "#define CONFIG_MK_RAM
8192" in config.h .

Example:

	FOO:HAS_BAR,BAZ=64

means:
	- the name of the board config file is include/configs/FOO.h
	- the generated file include/config.h will contain these
	  lines:

		#define CONFIG_HAS_BAR  1
		#define CONFIG_BAZ  64

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
[wd@denx.de: edited commit message; added code to deal with an
optional board configuration name]

Signed-off-by: Wolfgang Denk <wd@denx.de>