Update checkpatch configuration

Disable the following check which are not relevant for the project:
  - UNNECESSARY_PARENTHESES: parentheses make reading if conditions
    safer, so let's keep them.
  - PREFER_DEFINED_ATTRIBUTE_MACRO: we prefer ACLE "standard" formats
    instead of macros wrapping these
  - BIT_MACRO: no BIT macro in the project

Change-Id: I9046915f4878b17b1c186e4e4f231d3a3dd9320d
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
1 file changed