cosmetic: boards.cfg: fix some maintainers fields

Add a whitespace between the name and the email address.

When switching to Kconfig, the first version of MAINTAINERS files
will be generated based on the boards.cfg file.

So, the maintainers field should be corrected even if it is a really
minor fix.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Simon Glass <sjg@chromium.org>