Currently sm501fb_crtsrc_store() won't allow the routing to be changed via
echos from userspace in to the sysfs file.  The reason for this is that the
strnicmp() for both heads uses a sizeof() for the string length, which ends
up being strlen() + 1 (\0 in the normal case, but the echo gives a newline,
which is where the issue occurs), this then causes a mismatch and
subsequently bails with the -EINVAL.

In addition to this, the hardcoded lengths were then used for the store
length that was returned, which ended up being erroneous and resulting in a
write error.  There's also no point in returning anything but the full
length since it will -EINVAL out on a mismatch well before then anyways.

sizeof("string") is great for making sure you have space in your buffer,
but rather less so for string comparisons :-)
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Acked-by: NBen Dooks <ben-linux@fluff.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>