Staging: bcm: Bcmchar.c: Renamed variable "Bufflen" -> "buff_len"

Renamed variable "Bufflen" -> "buff_len" in
bcm_char_ioctl_reg_read_private().

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>