[media] em28xx: fix eeprom data endianess

The data is stored as little endian in the eeprom.
Hence the correct data types should be used and the data should be converted
to the machine endianess before using it.
The eeprom id (key) also isn't a 32 bit value but 4 separate bytes instead.

[mchehab@redhat.com: Fix CodingStyle]
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>