[media] xc4000: code cleanup

Various coding style changes:
  - removed unused / commented out code
  - changed C++ style comments to C format
  - renamed functions and variables that included upper case letters in the name
  - removed tabs from module parameter descriptions
  - replaced the use of XC_RESULT_* with standard error codes

Signed-off-by: Istvan Varga <istvan_v@mailbox.hu>
Cc: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>