console: fix out-of-bounds read in dputc(/dev/*, ...) ...

Trying to output a single character via
	echo -a /dev/serial0-1
currently results in garbage output after the newline, because console.c's
fops_write discards the buffer length and passes the buffer to
(struct cdev)::puts which only handles NUL-terminated strings.

Fix this by amending (struct cdev)::puts with a new nbytes parameter,
which is correctly propagated. All this functions now return at most the
nbytes parameter they were passed in. This fixes __console_puts, which
used to count new lines twice in its return value.

Fixes: b4f55fcf35 ("console: expose consoles in devfs")
Cc: Bastian Krause <bst@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

efi: add serial driver support ...

So now we can stop to use the efi-stdio as this driver
print on the Framebuffer and the serial at the same time.

This is specially usefull if we want to use the framebuffer via efi-gop for
something else.

Do not forget to disable the efi-stdio device before enabling the console
otherwise you will get double printing.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>