rt2x00: Fix efuse EEPROM reading on PPC32.

Fix __le32 to __le16 conversion of the first word of an 8-word block
of EEPROM read via the efuse method.

Reported-and-tested-by: Ingvar Hagelund <ingvar@redpill-linpro.com>
Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
CC: <stable@vger.kernel.org>
Acked-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>