[U-Boot] [RFC] Replace {fat, ext2}load by load in default env settings

Hi,

I would like to replace 'fatload' and 'ext2load' commands by 'load' command in default env settings such as loadbootscript, loaduimage, etc. for all boards. That way, the load commands are independent from the filesystem used.

Is there any objection?

If everyone is ok, I could submit a patch.

Guillaume