Fix some spelling mistakes in bbclass files
(From OE-Core rev: ed484c06f436eea62c5d0b1a2964f219f3e5cb61)
Signed-off-by: Maxin B. John <maxin.john@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>