binman: Don't show image-skip message by default

binman: Don't show image-skip message by default

This message is not very important since it is simply indicating that the
user's instructions are being followed. Only show it when the verbosity
level is above the default.

Also drop the unnecessary extra newline on this message, which causes two
line breaks.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>