Driver was reporting invalid raw read values for MAX6675 on big
endian architectures. MAX6675 buffered mode is not affected, nor
is the MAX31855.

The driver was losing a 2 byte read value when it used a 32 bit
integer buffer to store a 16 bit big endian value. Use big endian
types to properly align buffers on big endian architectures.

Fixes following sparse endianness warnings:
warning: cast to restricted __be16
warning: cast to restricted __be32
Fixes checkpatch issue:
CHECK: No space is necessary after a cast

Signed-off-by: sayli karnik <karniksayli1995@gmail.com>
Fixes: 1f25ca11

 ("iio: temperature: add support for Maxim
thermocouple chips")
Signed-off-by: Jonathan Cameron <jic23@kernel.org>