staging: fbtft: Add check on strlcpy() return value

Return value of strlcpy() is not checked. Name string is silently
truncated if longer that SPI_NAME_SIZE, whilst not detrimental to
the program logic it would be nice to notify the user. Module is
currently quite verbose, adding extra pr_warn() calls will not overly
impact this verbosity.

Check return value from call to strlcpy(). If source string is
truncated call pr_warn() to notify user.

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>