efi_loader: simplify running helloworld.efi

Currently when executing 'bootefi hello' we copy helloworld.efi to the
address identified by environment variable loadaddr. This is unexected
behavior for a user. There is no need to copy helloworld.efi before
executing it after relocation.

Remove the copy action.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>